Heads-up: I dug into this because I had the same panic last night when 'FanFiction.net' wouldn't load for me. First thing I do is check a couple of public trackers — I looked at DownDetector and scanned a few Twitter/X posts and a subreddit thread. If several people are reporting the same issue, it's almost certainly a site-wide outage or scheduled maintenance. Sometimes the site posts a short notice on its login page or on social channels, but if it's a backend database problem you might not see a friendly banner.
When it's only me, usual culprits are DNS hiccups, flaky Wi‑Fi, or a browser extension like an aggressive adblocker breaking scripts. I switch to mobile data or use a VPN to rule out ISP routing, then clear cache or try incognito. If that works, I know it's local. If nothing works on different networks and devices, it's definitely down for everyone.
If it is down for everyone, I usually go raid my offline story stash, visit 'Archive of Our Own' or Discord circles, or write notes for a new chapter. Annoying, but it nudges me to save backups more often — and I always feel weirdly calmer once I accept I can't control the server gods, so I read or write elsewhere until it comes back.