I know from the creator of Dominion Online[0] that he had to upgrade his servers since the start of the Corona crisis. Lots of new users, leading to all sorts of problems. He seems to have things under control now, though.

[0] https://dominion.games/

Want to try a looser, table-top style version? Email me cebraverde, at gmail.com

I was frustrated by the official online Catan and Colonist.io, so I made my own version.

They have a beta site that was less swamped last time we played. No rankings, but we didn't care.