I set up a WebRTC solution using signalmaster, simpleWebRTC and restund on my own server. I tried with 5 or 6 different people, and it all worked, except for one person who could not connect. I then asked that person to switch his internet to use his mobile phone's hotspot, and then it worked for him as well, which made me conclude that something in his router or whatnot was blocking the connection.
I don't have a lot of details, and I don't expect a specific answer, but is there anything that would stop the connection from being made between two clients in simpleWebRTC?