Chiming in here with consistent issues. It has thus far been 100% repeatable by trying to access "Watched Threads" except for the very first time after logging in.
...
BRB
edit:
So this time I logged out of my forum account, then immediately logged in. I first browsed all forums, then clicked Watched Threads, and it loaded. Then I went into a thread, and again tried Watched Threads and it worked. I thought oh wow that's more than ever before in the past 24 or so hours. Then I went somewhere else, tried once more, back to 502. And that appears to be consistent again.
side note: Logging on to this forum is a royal pain in the ass for me using LastPass. It does not autofill, and using a desktop I have to enter my master pass every time I manually copy a password to paste into a site. Which means navigating a few menus. I know, I know, #firstworldproblems, amirite? At least on mobile, fingerprints and Android's latest system autofill and LastPass interaction, make this a small but welcome hassle. Lack of autofill support isn't exactly a super security benefit nor obviously great at deterring spammers. Other methods can be used to deter bots as well. Oh and this doesn't work on Chrome or Firefox on Windows 10 using the LastPass plugins for each browser.