Satellite specific setup for proxy devices?

We are trying to put a DR network proxy host in another datacentre and I alter the proxy using "rhsm.conf" and by the "satellite-installer katello-proxy*" commands but it always seems to reject the new proxy host. I have flipped it back to the original network proxy host and it works fine.

The networks team swears the proxy host has been configured the same on both sites, is there anything at RHN level that detects different paths for hosts and rejects then?

Regards, Ian Dennison