502 Bad Gateway on every first attempt

Has anyone else noticed that attempting to log into this home site often fails the first time it's tried, with a "502 Bad Gateway" NGINX error on /login/login.htm? It seems like if I go to try again, it usually works on the second or third attempt, but never the first one. (If I log out and log back in after that, it also doesn't immediately recur; nor does it seem to recur if I try in a private tab immediately after logging into a normal tab. Possibly some kind of server-side session tracking affecting it?)

 I'm not sure if this is a Composr v11 thing or a home site-specific thing. I'd kind of assume the latter.

I too have been experiencing this issue.

Occasionally I get it first attempt logging in without the "remember me" option. I get it every time I try to use the "remember me" option.

I have the same problem.

It's a known issue.

When enabling "remember me", everyone's browser is sending a header request which gets rejected by Nginx with a 502 bad gateway for some reason (I find it strange it's a 502 bad gateway and not a 400 bad request). As far as I know, it's probably an issue specific to my server and not Composr itself.

I unfortunately don't know an easy fix at this time. I've tried disabling CSP to reduce the header size to see if the size was to blame, but no dice. ModSecurity is also set to "detection only" mode, and it's not detecting anything anyway, so that isn't the issue. There are no firewalls blocking it. I may need to run Nginx in debug mode and dig through the logs.

I also don't suspect it's Cloudflare because the 502 is being thrown by my server directly and not Cloudflare.