Thread:Support/Cannot login over HTTPS on translatewiki.net

For some reason I can't login over HTTPS on translatewiki.net. Browsing the site works fine, but POST requests on Special:UserLogin are always failing after a 30-second timeout.

I have to disable HTTPSEverywhere, login over HTTP, then go back to HTTPS (where I am then logged-in).

Request URL:

https://translatewiki.net/w/i.php?title=Special:UserLogin&action=submitlogin&type=login&returnto=Thread:User+talk:SiebrandLqtTest/Testishness,+12+Oct&returntoquery=lqt_method%3Dsummarize%26lqt_operand%3D27821 --- Request Headers:

POST https://translatewiki.net/w/i.php?title=Special:UserLogin&action=submitlogin&type=login&returnto=Thread:User+talk:SiebrandLqtTest/Testishness,+12+Oct&returntoquery=lqt_method%3Dsummarize%26lqt_operand%3D27821 HTTP/1.1

--- Query String Parameters:

title:Special:UserLogin action:submitlogin type:login returnto:Thread:User+talk:SiebrandLqtTest/Testishness,+12+Oct returntoquery:lqt_method%3Dsummarize%26lqt_operand%3D27821

Form Data:

wpName:Krinkle wpPassword:(hidden) wpLoginAttempt:Log+in wpLoginToken:1c6811e2885981685998b785dbc251cd

This has been going on for months now. Previously I thought it was a temporary server issue, but I've narrowed it down to the login procedure.