Solved: Slow Transfer Speeds on Synology NAS

Solved: Slow Transfer Speeds on Synology NAS

So you’ve got a shiny new Synology NAS and you’ve started storing files on it, videos, music and so forth.  Unfortunately, the file transfer speeds are so bad you’re considering buying a turtle and glueing a USB drive to its back to speed up file copying.

After hours of searching the net for an answer, in the end, I found the cause of my woes in a couple of little settings tucked away on the Synology – effectively my Synology NAS wasn’t even trying to use newer/faster versions of the SMB protocol.

To find and check this, perform the following steps:

Login to the Synology NAS and click on Control Panel:


Ensure that the SMB service is enabled then click Advanced Settings:

In Advanced Settings, set the Maximum SMB protocol to SMB3, I also increased the minimum SMB protocol to SMB2.  If your NAS is operating on a private home network, you may want to disable transport encryption mode (use at your own risk) and enable opportunistic locking:

For me on my Synology DS215j, this took my file transfers from around 5MBps to around 80MBps!

Bob McKay

About Bob McKay

Bob McKay works at Perfect Image, is a father, programmer and a self confessed techie-geek type.

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65 comments on «Solved: Slow Transfer Speeds on Synology NAS»

  1. Margaret says:

    Is it necessary to reboot after making the changes? I have the DS218j. First I had used Disk Station to do a 2-way sync on my desktop for the Pictures folder. SLOW. Next I synced the Music folder. Relatively faster. Now I am attempting to sync the Music folder on my tablet (SSD) remembering how much quicker the transfer was on the desktop. File transfer rate = 1 file every 8 minutes. It’s been several days and 473 files remain. This is beyond painful. Many other descriptive words. So in short, I’d like to try these changes now w/o having to start all over because of a required reboot. Thank you!

  2. Margaret says:

    Got my answer. When attempting the change, “Network Service will restart”. Guess I need to be patient….

    1. Micheal Espinola says:

      For anyone wondering, you can do this live. Your time machine backup or file transfers will quietly recover from the extremely brief disconnect. Networking at this level recovers all on its own. You’ll quickly see your time machine backup estimated time drop soon afterward.

  3. Will says:

    Thanks! Just wanted to comment for others that might stumble upon this. Don’t have a gigabit router so was looking for other options to speed up my 1.5mb/s speed. This really worked – cut a 90gb move from 16 hours to 3 hours.

    1. Bob McKay says:

      Hi Will,
      Glad it helped! 🙂

  4. Matt says:

    I was really hoping that would be the answer to my problem… unfortunately it didn’t do the trick 🙁
    However, my settings wasn’t setup as you prescribe. So I hope that a step in the right direction.
    Thanks for that.

  5. Giordano Bruno says:

    Good morning. Your hint made my month!
    Slow speed has been a problem for years for the 1812+: the max. was 25 at its best …
    I was even considering changing it for a newer model.
    Now speed is up to 110 which is perfect.
    Again: Thank you very much and all the best for you and your family.

    Giordano Bruno

    PS What is the transport encryption mode? What if I unable it?

    1. Bob McKay says:

      Hi Giordano, I’m glad it helped! The transport encryption mode adds encryption to SMB V3.0 for security but obviously like any encryption, it comes at a cost so may affect your top speed it its enabled (try it and see!).

  6. Ming says:

    Very helpful. Save my day. Almost return. Synology should put this on their site

  7. Cub says:

    The hints not work for me, still only getting 10.5MBs max transfer,
    Any advise?

  8. Clay Burch says:

    I can’t even access my nas. It keep saying authorisation required. Any suggestions???

    1. Bob McKay says:

      Hi Clay,
      I’m afraid if you’ve lost the credentials to your NAS you have a whole other problem my friend!
      If you can browse to network shares though, your computer must have some saved credentials you may be able to retrieve.

    2. GC says:

      Clay, There is a reset button on the NAS. Use it VERY CAREFULLY. The Synology web site will say something like hold BRIEFLY and it will reset the password. If you hold it too long it will do a complete reset and you will lose your data. So please, READ the web site first.

      1. Bob McKay says:

        Hey GC, Thanks for the useful comment!

  9. Sanjay says:

    How long do I have to wait for the \\Diskstation share to come back? Currently says “The Network path was not found”…

    1. Bob says:

      Reboot the PC after the change. I had the same issue and that resolved it for me.

  10. Craig says:

    You legend!!!! Cant believe Synology don’t advise this info!

  11. Adam says:

    I recently purchased and installed a Synology DS418play NAS, using WD 4TB RED drives. After finding Mr McKay’s page on the interwebs,I made the same changes to my NAS as listed above.

    Yet, it hasn’t solved the speed transfer issues. When moving three (3) ~4GB files from a PC to the NAS, with the NAS mapped as a network drive, the initial transfer speed is great…some 106mb/sec (Ihave the two NICs bonded, on a gigabit switch). Then, within a few minutes, the transfer rate falls off a cliff, dropping down to 5-6MB/sec.

    It appears to be an issue during a multiple file transfer, not a single file transfer.

    1. Bob McKay says:

      Hi Adam,

      When you say the issue seems to be when you’re transferring multiple files, are they concurrent or queued? I’m wondering if concurrent copies of large files will have the hard drive head dancing back and forth and it could be the slow down you’re seeing is the caches maxing out. What is your RAID configuration and do you see the same problems copying the same 3 files back to your PC *from* the NAS?

      1. EB says:

        Honestly, I want to throttle the people who suggested I buy a NAS and the replacement supposedly ‘better and faster one’. What a waste of money. I’ve spent the last 5 days trying to upload, transfer and get everything running and syncing smoothly!

        1. Bob McKay says:

          Erm … thanks for the comment Em.

        2. steve says:

          call me 🙂

  12. MB says:

    Hi, thank you very much, I’ve been seaching on the web for couple of hours before finding your solution. It works for me!

  13. Brandon says:

    Recently installed a DS218, and the upload speed is awful. I made the changes above and I’m still getting upload speed in the single digit KBs range. At this rate, it will take a century or more to transfer my terabytes of photos. Do you have any other suggestions?

    1. Bob McKay says:

      Hi Brandon, what have you tried and what is our setup? (e.g. Mac, PC, Wired, Wireless)

      1. Brandon says:

        Hi Bob, thanks for your response. The DS218 has a wired connection to my Netgear R7000 router. All of my computers are running Win 10. One desktop is also has a wired connection, but the computer where I store the majority of my data is connected via wi-fi (2.4GHz). So far, I’ve tried changing the settings specified above and rebooting. Upon rebooting, the upload speed jumped up to 175Kb/s…very briefly, alas. It then returned to <10Kb/s…

        Could it be the CAT5 cable I'm using?

        1. Bob McKay says:

          Hi Brandon,
          I doubt very much that the problem lies with the cable between the Netgear and the Synology but given both have Gigabit ports its probably worth putting a CAT6 cable in there anyway (negligible cost too). The speeds your seeing are so slow however that something else is amiss here and I’m guessing the issue is around the wifi. Have you done a test transfer from the PC that is connected to the Netgear via a cable? This should prove (or disprove) that the connection from the Netgear to the Synology is sound. What signal strength is your computer seeing? If you do a browser based broadband speed test on that computer, what speeds do you see? (I ask because that should theoretically show you the slowest speed on the whole chain which given the speeds above appears to be within your home network).

          1. Brandon says:

            Hi Bob,
            I was playing with it again last night and this may be a case of user error. I discovered the upload queue and got better visibility on what what happening. I did what you suggested about moving a single file (2GB) from the wired computer to the NAS, and it transferred in about 2 minutes. I tried the same file from wifi and got a similar result. I’m now moving the folders in smaller pieces (40-50GB at a time). Upload speeds bounce around between 1-5 MB/s…is this normal?

          2. Bob McKay says:

            Hi Brandon,

            There’s still a lot of factors to consider I’m afraid but the critical one is that MBps is not the same as Mbps (its all in the case), a MegaBYTE is eight times larger than a Megabit. If you are using, for example, the Wireless-G (since you said your wifi 2.4Ghz) then the theoretical link speed is 54Mbps (Megabits) now in reality this equates to a 25Mbps transfer rate. To measure this in MegaBYTES you need to divide it by 8 so we’re talking around 3MBps.

            The truth is, if you want to do heavy lifting in terms of file transfer you either need a cable or a dual band wifi. Personally I swear by Ubiquiti Wireless Access Points, the pro versions of which give me a real-world transfer speed of around 25 MegaBYTES per second.

        2. Neal says:

          I had the same problem with the DS218+, I was transferring a ~100 GB folder with lots of tiny PDFs and it was running at around 10 to 50 Kbps. The way I solved it was to zip up the whole folder and transfer it at once, which reduces the size slightly but I think the major gain is that there must be some overhead in opening and closing a transfer connection in the Synology software. Once, the transfer was finished I extracted the ZIP file on the drive. It’s not ideal but gets the job done.

          1. Bob McKay says:

            Hi Neal,

            I think this is really a general issue not just Synology, I used to see this all the time when copying websites across servers, etc. (as they tend to hundreds/thousands of tiny files), just zipping it use to drastically reduce the time on both Linux or Windows systems.

  14. Brandon says:

    Hi Bob,
    Thanks for the advice and information. Continued testing over the weekend, looks like it’s working well. I switched the wifi to 5Ghz (802.11ac according to the router manual) and uploads are generally 5-10 MBps (not Mbps) according to the upload queue. The key is to not try moving terabytes in one chunk, I think. I moved a couple folders >150GB and upload times were in the 12-24 hr range. Anyway, thanks again!

    1. Bob McKay says:

      Hey Brandon,
      I’m glad things seem to have sped up. One thing I hadn’t considered is that when copying multiple files from my PC I never do ‘concurrent’ copies, that is where you set a file copying, then separately set another copying, then another, etc. – this is because Windows isn’t smart enough to just push each additional file to a queue, it copies a chunk of each in a cycle, which means there’s a bigger admin overhead (and if you have an old HD, the read head will be jumping about a lot more). If you need to copy multiple files, I’d only do it where you are able to select them all at the same time and do a copy/paste (sometimes I’ll even move files on my PC to the same folder before moving them to my NAS to facilitate this).
      All the best

  15. johnrxx99 says:

    It worked for me. But why did it need to be changed – I was at 112 Mbps then dropped to 12Mbps for no apparent reason.

  16. Roger says:

    Thanks a lot, it brought me from 10 to 110 MB/s – been waiting so long to copy the files for a year until I googled and found this forum 😀

  17. andy says:

    hi bob my ds215j wit 2x10tb hdd in shr buut when i try and copy my 1Tb acronis system back up to usb hardrive im luck get 6MB/s which is slow when this drive does 80MB/s plus on my usb3 on pc. Your fix did not speed it up dsm 6.2… fully up to date

    1. Bob McKay says:

      Hi Andy,

      Thanks, just to be sure, are you copying over USB, wifi or ethernet? Samba (SMB) is a network protocol you see.

  18. Martin says:

    You, my good sir ROCK!
    Been uploading photos for days. Now I’m done in a matter of hours.
    Thanks a bunch and cheers

  19. Graham says:

    Thanks for this, new NAS and couldn’t understand why it was so slow on transfer. Applied your settings and rebooted, all is good. Thank you sir!

  20. Robert says:

    Great post. I was getting 4MB/s upload to the NAS drive from my laptop on wireless.
    Adjusted all parameters as listed above and that still didn’t work.
    Finally changed wireless to 5G and that made it jump to 10 MB/s for smaller files and 40MB/s for larger video files.
    I am sure more fine tuning to be done but it’s very usable now.


  21. RetroC says:

    Tried the settings suggested above but unfortunately did not have change anything for me.
    I have a DS218+ wired to router. Used to access it via powerline (650 Mbps) from my PC and got around 110 MB/sec.
    “Upgraded” my WiFi and now use Asus wifi card (Triband) to connect to TP-link Archer VR2800 router. Windows suggests the WiFi connection speed is 1700 Mbps which I was hoping would give me similar results to powerline. My current file transfer speeds are 5-8 MB/sec which is slower than my broadband. I think its a settings issue as file transfer between my Laptop and PC over WiFi are around 30 MB/sec. I have tried to switch from SMB to FTP but no change in speeds. Is there something I am missing. Any suggestion will be appreciated.

    1. Bob McKay says:

      I’d try the Powerline again (with the far end plugged in to the new Archer router), the idea being to to test the throughput from the Archer to the NAS (if its as fast as it used to be, you know its a problem with your wireless connection rather than that link or a protocol issue. Assuming that the test shows fast speeds via the Powerline, I’d try a couple of different options for connecting via wifi if you can (diff adapter, tablet, mobile, etc.) and see what throughput you get. All I can think of I’m afraid!

  22. SyVo says:

    Thank you! It work great.

  23. Trueqap says:

    :)) Thank you!

    from 40 to 780 MB/s with 5g WIFI!

  24. Alex says:

    I recently bought the 918+. I have it and my previous Synology connected at the same gigabit ethernet switch (older version of TP-Link’s TL-SG1005D), however even after adjusting the Network settings on both Synology DSs, the transfer rate is still around 3 MB/s. Nothing has changed. How can I doctor this (I have no problem exchanging parts of the hardware) to finally get solid transfer rates between them?

    1. Bob McKay says:

      Hi Alex,
      Too many unknown factors here to be able to offer any advice I’m afraid:
      Where to/from are you doing the copies? (device types, etc)
      What type of connections are the devices using (I’m assuming the Synology units are wired but if using a PC, is that on wifi?).
      Have you checked resource monitor to see what speeds the Synology units say they are connected at? (if you have a bad cable, it could still be negotiating to 100Mbps even if both sides are capable of Gigabit).

  25. Carlos says:

    Hi Bob, I followed your recommendation but the issue persisted and my write/reads were still slow on a Macbook.

    However, switching from afp://…. to smb://… seems to have done the trick; speeds jumped from 5MB/s to around 100MB/s.

    Sharing just in case someone else forgets that this trick is for smb. Like I did!

  26. Jose Mercado says:

    For those still having the issue, as it does not apply to your setup. If you have dedicated 10GB connection to your NAS, make sure your iSCSI Targets are set to bind to those network cards. If all Networks are selected, you will notice that speeds will not always work as expected as it would be binding the connection to the slower Network card interface.

    go to your iSCSI manager, select the target section, select your Target and Edit. In there Select the Network Binding tab and use the “only selected interfaces” and check only the desired high-speed interfaces on the list. Bingo! now you have the expected speeds. Synology has a fantastic write up on MPIO (multipath) as well that is easy to follow.

    The above answer asumes you have properly configured the network interfaces on your server and NAS.

    1. Bob McKay says:

      If that’s your home-setup I have serious geek-envy!! 🙂

  27. JP says:

    You ar a legend. Went from around 20 up to 120! So a quick courtesy to say thank you.

  28. pickles says:

    I had already put the SMB3 & 2 min & max, but hadn’t disabled Transport Encryption Mode and now i’m uploading over wifi at 15 MB/s and have uploaded 2 gig in a few minutes, which took an hour before. So Thanks!

    The only thing i’m not sure about is I still have the ‘Enable SMB2 Lease’ ticked, as when I went to untick it, it warned “If you disable SMB durable handles or SMB2 lease, the Bonjour Time Machine broadcast via SMB will be disabled”. Which sounded bad as this is a Time Machine backup i’m doing so I left it ticked for the time being. Will that make much difference? Oh, i’m on Mac.

    1. Bob McKay says:

      Hey Pickles, glad this helped. Regarding the Time Machine Broadcast I’m afraid I’m not an Apple guy so can’t help, hopefully someone else here may know.

  29. Paul says:

    I want to use my Synology DS718+ to backup 2 Win 7 PC’s, one with an Ethernet link (PC-1) the other wireless (PC-2). Each PC has an external USB drive and a NAS user folder mapped as a PC drive. I can’t do unattended late night automated backups since the NAS maps disconnect after some idle period. I did a backup on PC-1 to it’s external USB drive and copied the 110GB file to the NAS drive at a good rate in about 45 min. That won’t work for PC-2 since the wireless transfer rate is far too slow. I’m thinking about adding a PowrLine Ethernet link from my Router to PC-2 (no easy way to run a cable) and would appreciate any thoughts on this.
    I also have 3 more PC’s I want to connect and am thinking of adding an 8 port Ethernet switch but not sure if I can still set fixed IP’s for each user.

    1. Bob McKay says:

      Hi Paul,

      This really depends on the type of backup you’re doing, these days I generally ‘image’ my PCs shortly after a clean installation and manually copy the image to the NAS. After that, just backup documents, etc. to the NAS directly on a schedule. You should need to map network drives, just create a shared folder on the Synology and use the UNC path to it (\\NASNAME\SHAREName\) – provided your machines are using your local router for DNS, this should work fine. In terms of fixed IP addresses, again you should really need them – just use the UNC paths of the PCs (e.g. \\PC1\). I’ve used powerline adapters quite a bit as my previous apartments were solid concrete & rebar, they worked pretty well and from what I read, they have gotten a LOT faster since then. Just remember that the sockets generally need to be on the same phase and sometimes you can get interference from other equiment (I used to have a cheap laptop power adapter that would kill powerline connections when it was plugged in to the same ring main).

  30. jp says:

    these settings did nothing for me. Still in the sub 10 b/s, transferring 1GB takes almost an hour.

    1. Bob McKay says:

      Hi JP,
      This seems like something else is going on there, without any details its impossible to help however. For example is it wired or wireless, what is the theoretical speed of the connection, what operating system are you running and what is the data your copying (e.g. 1 1GB file or 1000 1MB files)

  31. Smithers says:

    Nice info! I have a DS216SE and since a week or 3 transfer files is so slooooow. It start 2 sec with 30mb and then drops to 1mb and 366kb and 0, back to 1/2mb and 366kb and 0…..after checking i’m seeying my diskspaces runs up to 100% and i think that is the bottleneck. I have 2 reolink camera’s attached but i disabled them testing and no difference. I tried your stuff above but nothing seems working….any suggestions? thanks in advance!

  32. Rxs says:

    hi.. this seems to be a productive thread,,
    I’ve searched high and low for the issue i have!
    I’ve got the Synology DS418Play with four 2TB Seagate Ironwolf NAS drives. even with a direct wired connection to the NAS, I am unable to get more than 10mb transfer speeds. Its rather sad! I’ve been at this for at least 6 months now to no avail!
    any help will be really appreciated

  33. Rockit99 says:

    Well that did it for me and I thought I’d set the USB to ‘3’ already!

    Thanks for the tip!

  34. Bjorn says:

    I also had data transfer problems. Alle Cat6 cable, gigbit switches. Everything checked with testers, I was going crazy.

    Eventually a pro network friend of mine asked: do you have a Sitecom switch in your network? Yes I had one, after replacing it with a proper switch all is extremely stable at 115MB/s.

    Do you have a Sitecom switch? Do the following:
    Disconnect all cabels, place it on the floor with a bit of room around it, then smash it intensively with your foot until only tiny pieces are left, THAT’s my recommendation for Sitecom hardware!

  35. Homer says:

    The instruction above didn’t help. Finally solved for it with these settings:

    Under File Services -> SMB/AFP/NFS
    Max SMB – SMB3
    Min SMB – SMB2
    Encryption – Auto
    Enable opportunistic locking

    Under File Services -> Advanced
    Enable file fast clone
    Enable Windows network discovery to allow file access via SMB

    On Windows 10, turn off SMB 1.0 and turn on SMB Direct

    Hope this helps. Good luck

  36. mulder says:

    No luck on a DS918+ write performance on gigabit LAN between a PC with an SSD can only push files to this NAS in RAID 10 at 20MB/s and read at 50MB/s? I have RAID1 IOMEGA NAS’s from 15 years ago that are faster. SMH. SAD.

  37. Federico says:

    Thank you! The transfers for DS Photo (Android) are much much faster than before 😀

  38. Tom Mensink says:

    I applied all these settings on both NAS and Windows 10 PC and regretfully this all doesn’t work for me. Not with wifi and neither with direct USB cable.

    However the zip solution works: 250 MB of files in a folder which would take 11 hours with about 50 bits/second, is now copied as .zip file in a few seconds to the NAS!!

    Would still be nice though to get a speed on multiple single files which is about 100.000 times faster. Something must be terribly wrong.

    1. Bob McKay says:

      Hi Tom,

      The speed your seeing above is unfortunately not down to the connection speed of the Synology but purely the admin overhead at source and destination for moving lots of small files. This occurs even on a business network when copying to a high-end Windows server. I used to run a web design company and websites, by definition, are made up of thousands of small files – we used to see the same problem you’re seeing all the time.

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