Sorry, I don't know where is the best place post this, but this is a problem that has been going on for a long time. So, it's not related to forum itself, but it is related to forum settings related to Cloudflare.
Very often can't even log in in half an hour,
sometimes succeeds immediately, sometimes it still takes its 5-10 minutes.
This always happens when you log in. Very often when you open another topic on a new page, etc., so quite not predictable.
PS. I don't use any DNS or anything like that, I've been working with forums and websites for 15 years, I also know very well what Claudflare is - I also use it myself for testing purposes in some test forums, but have never had something similar. It happens with all these forums and websites, that uses browser checking before opening site itself.
My Request:
Please fix this problem or configure it to open the desired webpage after logging in, but not redirecting to this site, because it mostly also won't work.