I’ve been trying (unsuccessfully) to find an answer. Can anyone point me to some instructions on how to move a lemmy instance to another server?
Is it just a matter of copying the volumes and conf files to the new server and doing a docker compose pull & up from that new location?
No, these issues are pretty much by-design. In ActivityPub IDs are inherently tied to the domain on which they were created. Based on the nature of federation it is safe to assume someone somewhere will still go looking for that thing via the outdated URL.