Run this on both devices when a booth won't sync. It checks the three things that have to work, in the order they have to work, and tells you which one didn't. Nothing here touches your camera and nothing leaves the page except the address-discovery requests it is testing.
Each line is a way this device could be reached. host is your local network,
srflx is your address as the outside world sees it, and relay is a fallback server that
forwards traffic when a direct connection is impossible.
A relay is the difference between "works at home" and "works with someone in another country", and it is the one part of this that needs an account. Open Relay gives 20 GB a month free — hundreds of booth sessions — with no card. It used to hand out an open username and password to anyone; that was retired, which is exactly why booths stopped working across networks.
Sign up at dashboard.metered.ca, then paste the two things it gives you here. Saved on this device
immediately — for everyone else, put the same two values in the METERED block at the top of
js/room.js and redeploy.
Plain TURN credentials — one URL per line, then the username and password.