very strange. it works fine on Firefox Android (Fennec), but refuses to work on desktop Firefox or Chromium in Arch Linux. I can get to the "Enter Your Name" box, but it never goes past.
Before, chromium worked. now neither browser does in Arch Linux.
Yea, we did see issues with a small number of users behind a symmetric nat, which is usually found at work. We're looking into ways around this and we're open to suggestions :)
However, you may still be able to send files back and forth if both users are inside the firewall.