Ubuntu 13.10 (and possibly 13.04) seem to have a problem with self-signed certificates when authenticating to wireless radius servers (i.e. the GUPHYSICS wifi). This is discussed in a variety of places:
The problem seems to be that the Network Manager setup is adding the line:
even if you tick ignore when the system asks about certs the first time. Changing the value of the setting to false seems to fix this, although there is a possibility that it might get changed back by NM. (or delete the setting entirely, which seems to have happened on this laptop. Hmmm)
There is apparently a bugfix in place and rolled out to other distributions, but Ubuntu doesn’t have it yet…
Another way to fix this would be to get the certificate (probably in .pem format) and point the settings to it.