My Steam Deck Killed My Internet...

[Gerowen]

Actually, it was probably my Linksys switch, though somebody replied to a post I made on Mastodon and said they had seen other reports of this happening, so I'm not sure who to blame at this point.  I also posted this on on other forums, but thought y'all might find it informative or entertaining.

So anyway, I have the official Steam Deck dock from Valve, and use it quite a lot.  It is hard-wired to a Linksys SE3005 un-managed switch that is mounted behind the television.  This switch provides hard-wiring capability for the TV, desktop PC, Steam Deck dock and my Nintendo Switch dock.  Last night I was using my Deck docked in desktop mode with a wireless keyboard and mouse.  I had Firefox open and was using it to watch a YouTube video, but I had left the video paused for a while, while I did something else.  The display had went to sleep, but the Deck itself was still on and active.  Eventually I decided it was time to go to bed so I walked over and just unplugged the little docking cable from the Steam Deck, then used the hand-held controls to shut it down. 

About 10 minutes after going to bed my daughter came in and said that Plex on her kodi box wouldn't play the next episode.  I told her it was probably just the Plex app being finnicky and to just exit Plex and try again.  I didn't hear from her again and I went to sleep. 

At some point later, about 4:30ish in the morning, I woke up to alerts from my phone; e-mails from "UptimeRobot" informing me that Plex, Nextcloud, etc. were down.  At this point, I thought maybe it was just an automatic reboot, since I have the server set to automatically install system updates and, if a reboot is required, perform that reboot at 4-something in the morning.  But, it usually reboots so fast that uptimerobot doesn't have time to notice, so I did think it was a bit odd so I waited for 5 minutes or so and then tried to ping my server; nothing.  So, I got up, walked in to where the server and router and such are to check on things.

The server itself was fine, but the router was not.  All of the link lights were going crazy and I noticed that my phone had disconnected from the WiFi and even though the networks were visible, it kept trying and failing to connect.  The server itself was unable to ping the router, despite being hard-wired directly into it.  Pings mostly failed, or IF they succeeded, it was several seconds worth of latency (not ms, full seconds).  So, I power cycled the router.  When it first came up everything was great, for about 5 seconds, then it crashed again.  That's when I brought my laptop in and hard-wired it to the router so I would have a GUI and a web browser to use for troubleshooting.

Next I thought that maybe somebody was trying to DDoS my server, so I powered off my ISP's modem.  Still no good.  Next I thought, maybe it was some kind of a fluke or configuration error with OpenWRT.  I flashed the thing with OpenWRT years ago, and have upgraded it in place once and kept my old configurations, but got a warning about configs being incompatible between releases and had to do some fiddling with some settings to get things working again with the new firmware.  So, I hit the factory reset button to clear OpenWRT and reset it back to its default state. (Still OpenWRT, just not configured at all)  That still didn't fix it.  It was good for about 20-30 seconds, then it went back down.

Then I had the thought, maybe it was one of my devices causing issues.  So I unplugged everything except the laptop I was using to troubleshoot and power cycled the router, and, everything was fine, and stayed that way.  Reconnected the internet, waited, then the PiHole, waited some more, then the server, waited some more.  Then I connected the cable that runs to the living room.  Boom, dead.  Whatever the problem was, it was something to do with the living room, so I unplugged that cable again and went into the living room and one of the link lights on that switch was going wild.  Weird thing is though, the TV, Switch and desktop PC were all powered off and the Steam Deck was physically off its dock and in its case.  But the link light that was blinking was the one for the Steam Deck's dock.  I unplugged the cable from the back of the dock, waited 5 seconds, then plugged it back in and the link light came on and stayed solid, but wasn't blinking any more.  Went back to the router, plugged that cable back in, all good.

All I can figure is that for some reason there was data in transit at the exact moment I pulled that cable from my Steam Deck, and instead of just letting those packets die out and dropping them, either the dock (how much logic is really in the official dock from Valve?) or that switch, or some combination of the two, entered some kind of an infinite loop and launched a denial-of-service attack against the router.

I also power cycled the switch, just to be safe, and since the last backup I took of my configuration for the router's OpenWRT install was with a previous version of OpenWRT, instead of restoring that config and then trying to fix it again, I just decided to spend the next half hour manually reconfiguring everything from scratch in the router, and then made a fresh backup.  I also enabled a few more options like "SYN flood protection", configured the firewall to drop all "invalid" packets, etc. so that hopefully, if this happens again, maybe it will stay contained to that switch and not take down the whole network.

Everything has been great since.  It's not totally clear to me exactly what happened, but I just thought I would put this out there, perhaps as a cautionary tale.

I uploaded a short YouTube video describing the whole thing:

 

[goretsky Supervisor]

Hello,

Interesting.  Were you able to get a packet capture of the network traffic?

 

Regards,

Aryeh Goretsky
 

[Gerowen]

On 17/07/2023 at 22:35, goretsky said:

Hello,

Interesting.  Were you able to get a packet capture of the network traffic?

 

Regards,

Aryeh Goretsky
 

Negative, it never occurred to me to do a wireshark capture while it was going on.  If it happens again though, which hopefully it doesn't, I'll fire up a packet capture and then see if I can catch anything useful.

[Gerowen]

So I'm pretty sure, after talking to a few folks, that it is the USB ethernet adapter in the official Steam Deck dock that caused the issue.  I didn't get as many replies here so I thought I would post an update for the benefit of others who come across this topic.

I encountered more than one other person online who said they encountered the same problem, one of which on the LTT forums said that they never did figure out what the issue was and it never occurred to them that it might be their Steam Deck dock.  A commenter on YouTube replied that it's not uncommon for USB ethernet adapters to cause broadcast storms if the attached device is removed but the adapter still has power.  Somebody on Mastodon replied and said that they had the same exact thing happen, with a totally different make and model of network switch.  Across the comments I've gotten on various social media and forum sites, the only common denominator is having your Steam Deck dock hard-wired with ethernet.