I'm not sure those two settings should be compatible? If it's a private instance then it means it should not federate.
I guess it was an oversight regarding breaking changes. What error did you get? It might help some people who're experience similar problems.
Idea: every instance should have a community called "discovery" where admins post their instance's communities or recommendations
In the absence of relays it should be trivial for instance admins to follow each other's "discovery" community.
Only admins would be allowed to post to that community and they should publish a post on a weekly basis so that new servers who've just subscribed to their discovery community can fetch the post and show it to their users.
The post itself would contain an updated list of that instance's communities so that users from remote instances can click on them and subscribe to them. If an instance is very large, the weekly post could contain only the recommended communities and maybe some interesting instance stats or information.
Edit: to give some context, due to the way federation works communities of instance A are only visible to users of instance B if at least one person from instance B has already subscribed to that community.
Mastodon has relays to solve the kick-starting problem. But in the absence of relays it should be fairly easy to have a single specific community
Old Reddit VS New Reddit. Do designers believe that text scares people?
How windows Scandisk was dumbed Down over time to avoid "scaring the user"
This is just an example of why I created this community.
Is it just me or does filtering by "Hot" seemingly give better results than "Active"?
Active seems to order based on discussion length while hot lets you discover newer content that's also popular.
I changed my default settings to hot, since it seems to be better for discovery.
That is how it was at reddit during/before/relatively after the digg exodus.