Slow Ethernet LAN Transfer Speeds on the ReadyNas Duo

Posted on Posted in Joys, Techy

I have a ReadyNas Duo and for a long time have been getting very slow transfer speeds when connected to my desktop computer via ethernet. It transfers much faster via WiFi to my laptop, and even to my desktop when I disable LAN and enable the WiFi card.

This puzzled me for a very long time and was moderately frustrating. Streaming video wouldn’t work properly, file transfers would take aagggeeesss. I was getting average speeds of 100kB/s, so transferring a 1MB file would take 10 seconds, an average film of 700MB would therefore take nearly 2 hours – significantly longer than downloading it again on my desktop.

Anyway, I finally figured out what the issue was, thanks to this thread. It mentions dropping the MTU, which I had no idea about. I then did some digging and found out some interesting things. My understanding of this is not complete, so there may be some inaccuracies, but the basic understanding is sound.

The MTU (Maximum Transmission Unit) is the maximum size in bytes of a packet of data that can be transferred across a given network. All devices on the network will have an MTU value set in them. Some can have that value changed. For example most computers have it set as 1500, and the ReadyNas has it set as 1500. This post can help you figure out the MTU on your network. Mine was 1492, but both the NAS and computer were trying to use 1500.

This caused a horrendous decline in performance. I reduced the MTU on the NAS to 1430 as described by the post and immediately went from ~100kB/s transfers to ~7MB/s transfers – a 70x speed increase.

After some fine tuning and investigation, I reduced both computers MTUs to 1492 and the NAS to 1487 (no idea why – 1488 dropped us back to 100kB/s, 1487 runs at ~7.5MB/s).

Changing the MTU on the ReadyNas Duo is done via Frontview: Network>Interfaces (link is called Interfaces, but page is called Ethernet). There’s a textbox where you can enter your desired MTU. Enabling jumbo frames will automatically update the MTU to 7936. Changing the MTU doesn’t require a restart, but enabling Jumbo Frames does.

Now the NAS streams perfectly and transfers a lot faster over ethernet.

However, I read this post about a guy getting 40-50MB/s from a ReadyNas which got me intrigued. To do that, he used something called Jumbo Frames.

Although the NAS and my computer both support Jumbo Frames which can allow you to quadruple your transfer speeds, the limiting factor in my case seems to be the BT HomeHub 3 which only has 1 Gigabit Ethernet port, the rest are 100Mb/s ports, so I can’t connect the NAS to the desktop via Gigabit without buying a switch. Might look into that at some point.

19 thoughts on “Slow Ethernet LAN Transfer Speeds on the ReadyNas Duo

  1. Thnx for your blog. Several years my Readynas Duo was as slow as …. even when jumboframes where enabled, changing the MTU to 1487 opened a complete new chapter for me.

    Many thanks.
    Petje1972

  2. How would I go about doing this on a Mac? Via terminal?

    I’m a novice and genuinely need some help here.

    Thanks

  3. Nice post, and highly useful for what’s obviously some very counterintuitive settings. My READYNAS has also been very slow from the start (and on a full-gigabit network), but as it’s primary function was as real-time backup, I figured it didn’t matter all that much. Still the few times I’ve had to move any larger files or folders back, it always struck me as insanely slow! This certainly gave me a few areas to check into now. Thanks!

  4. Having changed my router recently I was really struggling with files on my ReadyNAS – serious hair pulling time – but a quick Google and a setting change and we’re back in business and flying along wonderfully. Can’t thank you enough for saving my already reducing hairline!!

    1. There’s a section in the post that covers it:

      Changing the MTU on the ReadyNas Duo is done via Frontview: Network>Interfaces (link is called Interfaces, but page is called Ethernet). There’s a textbox where you can enter your desired MTU. Enabling jumbo frames will automatically update the MTU to 7936. Changing the MTU doesn’t require a restart, but enabling Jumbo Frames does.

      You need to access ‘Frontview’ which is the NAS control panel which is accessed via your webbrowser by going to the NAS IP address, or maybe via Netgear software which you might have installed (I uninstalled mine so I don’t remember the name).

  5. I also own a Netgear ReadyNas Duo device and have experienced strange issues with transfer speeds to the NAS. I had my primary PC connected directly via Ethernet with Jumbo Frames enabled (9K) which was giving me speeds of about 35MB per second. When I wired my notebook directly to the router and ran it on the same mode I was only achieving 3.5MB per second which is ridiculously slow. When I disabled Jumbo packets on the ReadyNas Duo this went up to 15-16MB per second. I decided to ping the ReadyNas prior to disabling Jump Frames and realized that it does not accept packets larger than approximately 7000 or so even though this is what the setting defaults to. This could explain a lot.

    If I could potentially reduce the MTU of all devices to 4088 I believe I could achieve a greater speed without having to alter the settings each time. The problem is I am unsure how to do this on the ReadyNas 🙁 Does anyone have any suggestions?

    1. Nice speeds! I mentioned it above, but maybe not very clearly. You need to log into the admin interface of the NAS by navigating to it’s IP. Then:

      Changing the MTU on the ReadyNas Duo is done via Frontview: Network>Interfaces (link is called Interfaces, but page is called Ethernet). There’s a textbox where you can enter your desired MTU. Enabling jumbo frames will automatically update the MTU to 7936. Changing the MTU doesn’t require a restart, but enabling Jumbo Frames does.

  6. Thanks for this – great stuff 🙂
    I thought I had jumbo frames on my readyNAS duo (but was only still getting 3.5mb/s), I didn’t realise until you mentioned it and I followed the link to ‘jumbo frames’ in your post, that I had to tell the computer to use jumbo too!
    …now I’m getting 35mb/s write + 31mb/s read 🙂
    Strangely, if I leave jumbo frames on the NAS, but put the mpu back to normal on my computer (mac pro G5), I get back to rubbish speed writes but the reading speed shoots up to 40mb/s. None of this makes much sense I guess but I thought I’d add it for anyone wanting to get just fast read performance from the NAS. Say for instance someone who was bored of trying to turn up his NAS for years to get a useable speed and decided to give up and buy a different model NAS drive only to find his ‘old; NAS is now 3 time quicker than his new one 😉 oh well I’m sure I’ll find a use for the new one somewhere!

    thanks again 🙂

  7. Hello,

    I tried this and it did do a difference, but i’m having some strange issues. I have set the MTU on my computer to 1500 (actually that was the default setting) according to the guide you were linking for computers.

    When I changed the MTU on the readynas to, for example, 143 0 and started a transfer from my readynas to my PC the speed starts at 7,5mb/s (so far so good!), but then after about 5 minutes the speed reduces to what I had before, about 700 kb/s.

    I cant understand why? I tried different MTU’s for the NAS from 1430-1487, same result.

    Any advice?

    1. Hey Bill,

      Although perhaps not entirely clear in the post, you need to change both the computer and the NAS for it to work properly. Try changing your PC’s MTU to the same as the NAS and see if that works.

      Fergus

      1. Hello and thank you for the answer.

        I tried what you suggested but it did not help me. I set to MTU to 1430 on both the pc and the nas, I even tried 1402 on the PC as a long shot for the 28 bytes that the other thread was talking about.

        My hardware:

        NAS: Netgear duo pro 2, raidar version 4.1.7 i think.
        PC: Acer about 3 y old, still operating OK,
        Router: Technicolor tgv799

        Troubleshooting that I have done:

        – Direct connecting to the NAS from the PC, using a set of different MTU.
        – I have tried to use both a folder on the NAS with about 500 pictures and also a 2GB file.
        – I tried both ethernet ports on the NAS.
        – I tried my other network drive, which is a buffalo link station, there I get good reading speeds (about 10MB/s)
        – I tried using wifi to my router and then connection to the NAS, same bad result.

        Other info:

        – I am transferring all the files to my desktop
        – IP adress that i’m using for the NAS is static 192.168.1.100
        – I have selected the performance option about ‘deactivate journaling’-something in the front view settings.

        I have about 300GB important data to move out from the NAS, using the speeds that it is giving me now it would take weeks, unacceptable!

        By the way, I think I never get the speed of 7-8 Mb/s as I described in my first message, I think that was just due to that some data already existed on the drive somehow. I was running trials of data transfer and I aborted the transfer,deleted the files on my PC and then restarted the transfer.

        Sigh, this is really frustrating!

        1. Hhmm. If you never get a fast speed, and another NAS on the same network works fine, then perhaps an issue with your ReadyNAS. Have you turned Jumbo Frames off?

          Also, worth eliminating all other possibilities like faulty cables.

          I think you can also get issues if the MTU is too low so try something higher like 1470.

          Argh, I know these things are annoying.

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