Firefox fails to gather UDP ICE candidates after network change(ICE restart)

[shazzzzzzzz]

I am trying out ICE restart scenario on Firefox and here is the description

- User A calls User B(both users on same machine)
- Machine switches to new wlan(say wlan0 to wlan1)
- ICE connection state transitions to 'disconnected' for both users
- User A triggers renegotiation with ICE restart. Only TCP ICE candidates are gathered and call fails eventually

If the ICE restart is triggered without network interface switch, then Firefox gathers UDP ICE candidates as well and the call works fine.

The issue can be easily reproduced with WebRTC sample - https://webrtc.github.io/samples/src/content/peerconnection/restart-ice/

Here is the ice connection logs as well - https://drive.google.com/open?id=13MCbU2ta7aU9K2bVe_4-btf2XqDgYnfO

Tested on
- Firefox 60.2.1esr (64-bit) on Suse Leap 42.3 - Fails
- Firefox 62.0.2 (64.bit) on Windows 10 - Fails
- Chrome 69.0.3497.100 (64-bit) - Works