wifi: mt7921e cannot be connected from outside

[Shunran Zhang]

Hi all,

I am using MediaTek MT7922A22M PCIe WiFi + Bluetooth card, with Linux 
6.2.1 as well as 6.3.0, on AOSC Linux.

When I am connecting to my home WiFi, I am having some issues with its 
connectivity that feels like the machine is behind a firewall. I can ssh 
to other machines on the same L2 network, but not being sshed from 
others. I can send out multicast packages and they could be received by 
others in the same network, but their multicast packages never reach my 
kernel - no mDNS packages received by wireshark or any other package 
capture software, and setting iptables to log INPUT also do not show 
anything other than connections initiated by this Linux laptop. The 
output of avahi-browse -art is empty, even though there are a lot of 
mDNS traffic in my L2 network, including a printer, and a daap server, 
and other devices connected to the same WiFi works with them without issue.

I have checked my firewall settings, in which the firewalld was disabled 
and iptables only contains default ACCEPT. The same issue also 
disappears if I plug my laptop into the wireless AP using an Ethernet 
cable, or if I replace the MT7922 with an Intel WiFi card (currently 
using 7260).

While I do have some knowledge on the network and routing kind of stuff, 
I am not quite familiar with the kernel driver. Please advise on how I 
should debug that.

Sincerely,

Shunran Zhang