Bug#1136459: openssh-server: [regression] stopped accepting connections over the WLAN

On Thu, May 14, 2026 at 01:44:04AM +0200, Thorsten Glaser wrote:
>>Unfortunately, I’m unable to get either of the laptops to switch
>>APs (sudo iwconfig wlan0 ap …), but I did get an iwlwifi crash on
>>attempting that… so I cannot test changing Fritzboxen atm.
>
>That being said, I managed to take a pcap dump on¹ the 7330 (client).
>
>What I see there:
>
>1. c→s TC=00 tcp syn/ecn/cwr
>2. c←s TC=00 tcp syn/ack/ecn
>3. c→s TC=00 tcp ack
>4. c→s TC=02 ssh version+crlf
>5. c←s TC=00 tcp ack, no payload
>and a few seconds later c→s fin/ack, c←s fin/ack, when I pressed ^C.
>
>When I do a pcap dump on the 7430 (server), I see lots more, with TC=B8.
>
>So it seems like certain network devices default to blocking packets
>with the new default traffic class octet, which I think you’ll want
>to take upstream.

I think it would work best if you could take this upstream yourself.  
Since I have no access to your hardware, when upstream ask for extra 
debugging information, I'd end up just acting as a glorified relay, 
which I'm not very good at.

Upstream told me that they've had a total of two reports of problems 
with the new IPQoS settings, so I expect they'd be interested in 
additional reports of regressions.

I've CCed one of the main authors of these changes in case they can spot 
anything that would come down to a bad backport on my part; Job, see 
https://bugs.debian.org/1136459 for context.  Thorsten, if you could try 
the version currently in testing (or perhaps also the version in 
unstable), that would help to exclude problems caused by possible bad 
backports.

Thanks,