Whenever I attempt to set the URL for a new modpack I created, I get a 504 error. I can edit any of the other settings for the pack without difficulty, but editing the URL spins for a while and then times out.
Am I doing something wrong, or...? I've been trying for a couple hours, and I've had no luck so far. The modpack is called DefenseCraft, and the URL I'm trying to use is: http://newrepublic.us/DefenseCraft/v1.0.zip
EDIT: I found the issue. My server has an AAAA record configured, but my IPv6 link was down -- and apparently it validates using IPv6 by default.