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Re: RN102: Changing MTU from 1500 to 9000 & connection probl

ryanasimov
Aspirant

RN102: Changing MTU from 1500 to 9000 & connection problems

I worked on this with ReadyNAS tech support and they were unable to reproduce it. I have a simple network with an Apple Airport Extreme doing the routing and feeding an 8-port Gigabit switch. The switch is connected to a couple of printers, a Windows 7 PC, and 2 Macs.

I was using an Ultra 2 with Jumbo frames set to 9000 and all was well for the past 2 years. Unfortunately, Mac OS 10.10 doesn't play well with the Mac ReadyNAS Remote client, so I got a ReadyNAS 102 so I could use the more modern OS6 and ReadyCloud. I migrated everything over and everything worked well, though I noticed that throughput was less than the Ultra 2. I looked around the network settings of the RN102 and noticed it was set at its default of 1500. I changed it to 9000 and was still able to access it via my LAN, but ReadyCloud wouldn't display the shares. Changing the MTU back to 1500 restored ReadyCloud connectivity.

So... should I live with the slower throughput and keep the MTU at a trouble-free setting of 1500, or is there something that I or tech support have missed? BTW, the Airport Extreme doesn't have any way changing the MTU, but all the attached clients (except the RN102, of course) have been set to 9000, so that's something that has already been tried.
Message 1 of 9
StephenB
Guru

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

Did you do your Mac Remote test on your local LAN or over the internet? Is is easy for you to test both?

On the RN102 side, remote should look like a different "virtual" network interface - which can have a different MTU than the physical ethernet. You should be able to see that with ssh.
Message 2 of 9
ryanasimov
Aspirant

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

After changing the MTU to 9000 I can login to readycloud.netgear.com, but after displaying the name of my NAS it times out and says "Device Offline". If I connect to my NAS through my LAN by typing its IP into my browser the same thing happens. HOWEVER, if I use the Finder I can access the shares through the Finder.

I believe that SSH is a way of connecting to network devices through the Terminal, right? If so, I don't know anything about command line connections.
Message 3 of 9
mdgm-ntgr
NETGEAR Employee Retired

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

Is the NAS connected directly to the router or connected via the switch. If connected via the switch, what kind of switch is that?

Note also that the 312 would be the replacement for the Ultra 2 in our current product lineup.
Message 4 of 9
ryanasimov
Aspirant

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

The 102 is connected to the switch (a Netgear GS108) using the port previously used by the Ultra 2. I've tried the new 102 on each of the 8 ports with the same results I've described above.

I evaluated the 312 but decided the 102 was sufficient, as only 3 people total (and never more than 2 concurrently) use it for small document storage; no streaming or files larger than 10MB. I didn't need the additional network port, HDMI, or eSATA connection.
Message 5 of 9
StephenB
Guru

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

Did you try readycloud.netgear.com from your local LAN?
Message 6 of 9
ryanasimov
Aspirant

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

Yes; please see the 2nd paragraph of my initial post.

MTU 9000 = The 102 IS accessible via Finder on the LAN only.
MTU 9000 = The 102 ISN'T accessible from readycloud.netgear.com via LAN or from an outside network.
MTU 1500 = everything works, but throughput is slow.

I'd use the Mac version of ReadyNAS Remote, but it doesn't work with Mac OS 10.10
Message 7 of 9
StephenB
Guru

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

I think the second sentence is not clearly stated in your initial post.

I am guessing that the remote connection is attempting to use the 9000 mtu. That would result in IP packet fragmentation. The effect of that fragmentation depends on the specific equipment on the path to the netgear servers and back. Some equipment simply carries the fragmented IP packets which are then reassembled. Other equipment drops oversize packets and won't fragment. Some will drop fragmented packets because some DoS attacks use them. So the symptoms might vary depending on where the test is run.

Support could potentially look for that specific possibility (and not attempt to recreate your specific symptoms). You could as well if you can configure your setup to do a wireshark trace.

What performance are you seeing on the RN102 (with and without jumbo frames).

Steve B.
Message 8 of 9
mdgm-ntgr
NETGEAR Employee Retired

Re: RN102: Changing MTU from 1500 to 9000 & connection probl

What's the MTU for your internet connection set to? Does lowering that make a difference?
Message 9 of 9
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