With docker it is essential that you set PLEX_CLAIM correctly to attach the new server to your Plex account at the first start of your container. You only have 4 minutes to start your docker container the first time or your PLEX_CLAIM expires. And this CLAIM process will also only work the first time you start the container (test for existence of the file /.firstRunComplete). So if your new server was not attached to your Plex account (login via plex.tv), just remove the container and all volumes and start from scratch with a valid PLEX_CLAIM.
