Thanks for the replies everyone and thanks to Q2 for looking into this (Hope you’ve got a cream for the thunderclap).
Desktop-PC+Firefox = white screen of nothing.
Desktop-PC+Opera (with or without VPN enabled) = “This page isn’t working / forums.fanedit.org is currently unable to handle this request.”
iPhone+Safari (wifi and 4G) = white screen of nothing.
Desktop-PC+Chrome = Forum seems to look fine, until I try to login to my forum account. It says logging in is successful and then a white screen pops up “This page isn’t working / forums.fanedit.org is currently unable to handle this request. / HTTP ERROR 500”. After that the forum is broken because I can’t logout again (or login).
Desktop-PC+IE = Same deal as Chrome. Same error “HTTP 500”. Again, I can’t logout now, so the forum isn’t accessible for me on any browser of device.
P.S. I was already logged into Firefox, Safari and Opera prior to the error starting to happen. So this looks like some kind of login thing? Account stuck in login-limbo?)
P.P.S I can access the ifdb admin panel as normal (so far).