Now, I’m very new here too but maybe I can provide a little insight.
I tried to login on multiple instances before I realized I can only login on the one I signed up for. But if you got to the main page on where you signed up, you should see a toggle, subscribed/local/all. Select all and it’s the equivalent to r/all I think. You can also search communities (subreddits) both locally and under all (which is federated) here a link make sure it says all on top if you want to search all instances.
Now, I’m very new here too but maybe I can provide a little insight.
I tried to login on multiple instances before I realized I can only login on the one I signed up for. But if you got to the main page on where you signed up, you should see a toggle, subscribed/local/all. Select all and it’s the equivalent to r/all I think. You can also search communities (subreddits) both locally and under all (which is federated) here a link make sure it says all on top if you want to search all instances.