Have you verified that the ports are reachable - be default, if you set the base port to 48000, you'll need the TCP range 48000-48030 open bidirectionally. You might also need ports 80, 8080,8008,443, etc. depending on other needs.
And on your hub you may need to set up an entry in the hub list.
There are some diagrams in the hub documentation that go over this sort of setup too.