Admin PSA: please ensure your IPv6 outbound and inbound work on your instance. With Mastodon 2.2.0 or so (which a lot of instances still run) people can't federate with you because it will try IPv6 first and then give up. Disabling AAAA records isn't good enough if you run 2.2.0 because it won't retry outgoing either.
You'll wind up with assloads of missing posts.