when you say you migrate, are you using the GUI to move things ? can't you just do a copy of the database and storage to the new VPS so everything goes back online ? (redis don't really need copy, unless you want to keep sessions and cache alive)
if your usinjg the GUI, if it's complaining on the new server, maybe it's the migration host which is the server hostname from outside (maybe if you add hosts directly in the old VPS containers, maybe you can trick them to not use a real DNS name)
but i really don't know for the GUI as i only did a direct copy of the docker volumes to the new server and it worked fine for me
aslo i didn't mention but do a backup of all the data in case you haven't already, just in case something bad happen