I can't figure out how to have sync visit a community I have an address for. !main@selfhosted.forum in search doesn't work. I see no other way of doing this. Am I missing something?
If no one from your instance has subscribed to that remote community yet it won't load. It's a quirk of how federation works. Once a single person from your instance subs to that community then your instance will begin to sync and federate content. To get around this, the easiest way is to:
Click the home icon (shapes like a house) and set your home instance
Then search for the community you want to subscribe to
Open the link and it'll open the community in your home instance where you can subscribe
If that still doesn't work then go to your home instance community search page and search the full URL of the remote community. You may have to search for it twice for it to show up. Then you can hit subscribe. Once you do this, not all content will be fetched retroactively. I think just a few weeks of posts and comments, but all future content will federate properly
Edit: when I click the link in your post in sync, it opens just fine for me
This will need to be substantiated by someone who knows this for sure, but I believe the way this works is that when you search for a community that's not on your home instance from in the app, the app asks your home instance if it knows any communities that match the search string. If your home instance has never loaded the community you're looking for before that time, it won't come up in search, because your home instance doesn't have it federated yet.
However, when you click on the community link, the app is asking your home instance to load from , and so your home instance will first federate with (read: subscribe to) that community, then return the results to your app.
Your home instance now knows about that community, and should now be able to return it in search.
I don’t use sync but if you’re able to search and visit it with an error you may just need to try it again if it wasn’t on your instance already. It’s finicky when the community isn’t known by your home instance.