After enabling wifi you have to execute the action again. I think it's unintuitive but it wouldn't be trivial to change:
https://github.com/koreader/koreader/issues/1128
Aside from that on the stable channel there wouldn't be any updates yet regardless of the server.
In my experience and opinion the latest nightly released on GitHub at the time of writing is very good:
https://github.com/koreader/koreader....04.30-nightly