We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
#5791 - Login page might trigger upstream sent too big header error in NGINX
This happens on enquire on new IPs when someone tries to log in and needs to verify their IP address.
Could also happen with "remember me" on the login page (though it's random).