So, !gnusocialde is back. This is what happened:
The server was at limit for a while now. CPU load was constantly extremly high. By the "Patrick-Breyer-Incident" starting on last Saturday a lot of users joined. I opened registrations temporarily for that.
That was a bit too much for little server-y and it gave up during Monday.

On Monday evening I shorthanded initiated switching to a new server. 30GB database as well as 150GB user data migrated over night and during today I configured everything.

In the meantime everything should work okay but I'll have to do some optimizations still. There might be some outages incoming.

Thanks for your understanding, the many (!) helping offers and especially for you patience!