Blue Post
Original thread hosted on Blizzard's official forums.
Can't log in - "You login attempt has timed out (Code 300008)"
View on Blizzard forums:
https://us.forums.blizzard.com/en/d4/t/cant-log-in-you-login-attempt-has-timed-out-code-300008/245811/17
The team is aware of this issue, and are working on it