I've had a few questions about trouble accessing other communities from here.
First and foremost, I request you to be patient, lemmy is...alpha software at best imho. There's 200+ issues on github right now and very few maintainers. No one expected things to take the turn they did within a matter of days, but here we are :)
Biggest known issues:
Websocket support is being reworked
This is out of my hand and I can confirm that its busted. I tested locally and the current main lemmy backend branch is incompatible with lemmy-ui branch. Can't even login if you set everything up locally.
Accessing communities from other instances is flaky
Good news is that there is shoddy workaround. Say you want to access c/gaming from beehaw.org. Enter the full url https://beehaw.org/c/gaming in your search, it won't show up, click search ~~a couple times~~ then wait a sec, then enter just gaming and it pops up magically.
No high quality mobile apps
There's jerboa for Android and mlem for iOS. Both are under heavy development. Thankfully the website works fine on mobile...mostly.
PS: I'm not a lemmy maintainer, just a hobbyist self-hoster and professional Rust developer trying the fediverse as much as y'all are :)
lemmy_server development team needs some Database Management Experts to identify the key SQL queries and optimize them, possibly denormalize data and suggest wheres application caching can be done.
It looks to me like /communities list is fetched from SQL every time a user brings up that page, that data could be at least cached for 2 minutes in the Rust code. Or even add a trigger to generate a flat table when a new insert is done (addition of a new community).
So far, there hasn't really been but a couple people looking at the SQL problem of scaling:
https://github.com/LemmyNet/lemmy/issues/2877