https://wccftech.com/diablo-ii-resurrected-launch-issues-workarounds-fixes-updates/

Tell me if you’ve heard this one before – Blizzard had launched a new remaster of one of their classic games and yet server issues and other problems have rendered the game nearly unplayable. Diablo II: Resurrected arrived yesterday, and players have been beset with issues, ranging from being locked out of the game, to characters losing progress or disappearing altogether, particularly if you’re playing offline.

Blizzard promises they’re working on the server issues and manually unlocking characters, but no actual patch has been offered yet, and players continue to report widespread issues. In a post on the Blizzard forums, the studio promises they’re working on an array of issues.