RPC Error for child domain Exchange servers

Hi Internet, 

I am having an issue with connecting to the RPC service on my test Exchange servers when trying to update the exchange certificates. 

Layout as follows;

contoso.local - Production; 2x2013 Exchange servers CU11

test.contoso.local - Test; 2x2013 Exchange servers CU11

When I try to connect to the server to modify certificates in the ECP I get;
Cannot connect to the remote procedure call service on the server named TEST SERVER. Verify that a valid computer name was used and the Microsoft Exchange Service Host service is started.

I Remote to the server it-self, fire up powershell; it connects to the correct server;

I and run; get-exchangecertificate -server <TEST SERVER.test.contoso.local>

the following is returned;

Cannot connect to the remote procedure call service on the server named TEST SERVER. Verify that a valid computer name
was used and the Microsoft Exchange Service Host service is started.

I have even tried;

get-exchangecertificate -server <TEST SERVER.test.contoso.local> -domaincontroller <DC.test.contoso.local>

with the same response.

The server has been rebooted and all services are running;
*.test.contoso.local is added in the accepted domains as an internalRelay

I suspect it is to do with the fact that they are in a child domain but cannot figure out what it is. 

Thanks in advance