Guys, anything? Anyone? Please let me know if the question doesn't make sense.
The reason I am looking for this info is that sometimes my users do get media in either direction. They establish a call to FS and I confirm that all the signalling went through and there is no "audio DTLS packet not written" error in the logs. However, there is no sound coming in either direction. Then 30-45 sec later, FS writes a message "No audio stun for a long time"
In this particular case it was fixed by switching to a different ISP (so definitely not a FS or WebRTC problem). but I would like to try to provide more information to the network people about what to look for.