[panzerschreck]

So this is an odd one.

I'm running DD-WRT v3.0-r41218 on my WRT1900ACSv2. I have one ethernet cable running from my modem to the WAN port of the WRT and one ethernet cable running to a TP-Link 16 port unmanaged gigabit switch. All my wired devices are connected to the switch.

I have the WRT configured as a gateway, wifi and internet connectivity work like a charm.

The problem is: periodically, but with no real pattern all my wired devices lose LAN and WAN connectivity. Only a reboot of the router helps. I cannot even ping the router from any wired device.

I used a different switch, same problem. Reflashed DD-WRT, same problem. Looked at different VLAN settings, but nothing seems to help. I'm at a total loss.

Has anyone experienced anything like this? Any input is greatly appreciated. I can provide any necessary information, but since I don't really know where to start I'd rather provide material on request.

Sincerely,
panzerschreck

[SurprisedItWorks]

I haven't seen that particular behavior, but when my routers of that same model get weird, the first thing I check is the CPU temp. Had two that behaved erratically until I added USB fans (so I added fans on the others also, as a precaution). Based on my modest experience, if your temp is 75C or higher, it could well be your problem. With the fan, my temps drop from 72-75C down to 55C or so. Electronics tend to last longer when cooler, so it can't hurt. I'm using a $12 AC Infinity 120mm fan and just setting the router on top of it with the airflow up through the bottom of the router.

Also, since you mentioned VLANs, I'm not sure that the VLAN tab in the GUI applies at all to our two-cpu architecture. Perhaps it does in the case of using VLAN tagging to have a WAN connection do double duty or something. I'm not sure because I've never needed to explore that. But if you ever need to split the set of four LAN ports into two (or more) VLANs, see the link in my sig below for the usual approach for this router. Much of the discussion is a year or so old, but the setup still works perfectly for me as of build 40784.

[panzerschreck]

Hi and thanks for your reply!

I think I have found the culprit, and in a way different direction than I ever expected.

I have flashed my router back to factory settings and then to the newest release. I have then refrained from importing an old settings backup but have instead configured everything that is necessary manually. I also stayed away from the VLAN settings and left them default. Same problem happened about 30 minutes after the router was running with the new settings.

I then thought about what devices I added to the network since the problem appeared and realised that it started around the same time I added a Lenovo Ultra Dock for my Thinkpad. It also has an ethernet port that is forwarded to the Thinkpad.

The next time the problem occured I just unplugged the ethernet cable from the dock and waited. Surprisingly, all my other ethernet devices came back online after a few minutes.

So it seems like DD-WRT may not be the problem. It is more the interaction between the Lenovo Dock, the switch and DD-WRT.

I will still look at your temperature advice though. I have noticed the router getting quite hot in the past, too.