Peer to peer connection fails between Firefox and other browsers (Chrome & Safari)

[JulienVig]

Trying to train a decentralized task (e.g. mnist) in local with peers running in different browsers fails for a user running in Firefox.
The training fails if there is at least one user in firefox and some other users are running in other browsers. If all users are in Firefox the training works fine. A mix of chrome and safari with no firefox also works.

The issue seems to be that chrome and safari doesn't manage to send data to firefox via webrtc.

If some users are in firefox and other are not, after hitting Train collaboratively, the peers seem to be able to establish webRTC connections successfully but peers are not able to send contributions to each other:

• when peers running in chrome or safari try to send a weight update to firefox, this error is triggered RTCError: Failure to send data
• add receiving firefox users display the error: From cf726cd7-af2e-478b-89b3-58fc3a185bb7 : peer 2e884816-076b-405b-987e-8f7a05fb8aa0 closed connection followed by Uncaught (in promise) Error: cannot send after peer is destroyed