Completely confused

I have a setup using mediasoup with a media server which connects to the client via a TURN server to produce a live stream. The livestream is working for most clients who connect, successfully setting up an ICE lite connection, decoding the received video and audio packets etc… and producing a livestream.

However, there is one client who when attempting to view the livestream does not decode any keyframe or video packets. They are receiving video packets but not decoding them at all, instead the PLI and Knack count simply keeps rising with no video playback, just a black screen. The weird part is that the audio is being decoded as expected, the client has a successful ICE lite connection, is connecting to the TURN server, etc… everything else in the process is just as you would expect besides that the video frames are not being decoded.

The client has tried every browser, has tried using cellular data, multiple devices, etc… and the issue persists.

I’m completely stumped as to how to continue debugging this issue. The client also has been able to view livestreams in the past and the problem has seemingly randomly arisen. What steps should I take to further debug this?