https://secure.runescape.com/m=news/login-issues---27th-march?oldschool=1
Apologies for the inconvenience all. We're investigating.
This thread was added on March 27, 2020, with posts from JagexSween.
Original Post
https://twitter.com/OldSchoolRS/status/1243603983127765000?s=20
I would have them check cached login. One example would be, on mobile I can login with cached credentials, but clearing them gives me an error when logging in again. Whatever login performance they did could of caused AAA issues. /u/JagexSween
Edit: legacy/email accounts receive a 1 minute login error to your login server as well. continued edit... I'd check your DC or failover to another logon server.
We published the cause of the issue in the post. It's unrelated to anything our side. Our worlds were enduring an attack.