Timeouts might be from the server struggling since the reddit blackout is bringing in a lot of users at the same time right now. I'd wait a few days and see if the issue disappears or maybe a second account on a lesser known instance might help.
I’ve noticed (although on the .ml instance) that even whenever GET requests go through fine (albeit a bit slow) POST requests don’t actually return a response. After 60 seconds they will timeout, even if the operation actually does complete successfully. This happens mainly on voting and making comments from what I see.
I think its best to just use the lemmy web instance interface to subscribe to communities on all kinds of instances, and then they just show up in Jerboa. :)
Timeouts may be because you are using an overloaded instance like lemmy.ml when you should spread out on other instances. :)