Unable to log in: Too many failed login attempts

[WarmCat]

I can't log into the game.
I noticed this problem when trying to connect and play multiplayer with my friend, which was giving authentication issues.
I removed player-data.json in an attempt to re-log in.

When Factorio loads up and asks for my username password, I get the following error:
Too many failed login attempts. Please try again later. If you have forgotten your password... etc etc.

I haven't forgotten the password, I can log into the website fine.

What is going on here?

Update: I managed to log in by tethering to my phone, but I still can't connect to any multiplayer sessions. Error is the same, too many login attempts.

[vinzenz]

Please write to support@factorio.com including your log file and factorio.com account name.