To troubleshoot problems with a specific remote user or remote wifi network ask the remote device user to click on this link:
https://networktest.twilio.com/?region=eu-west-2
To test your browser click this button:
You should see the following screen. All checks should pass prior to a session.

Bandwidth requirements
Low-Res Video (240×180) – 240 kbps
SD Video (640×480) – 865 kbps
HD Video (1280×720) – 2,000 kbps