Error connecting to another GPOADmin server instance from an untrusted domain\forest (4380915)

When you attempt to connect from one GPOAdmin instance to another instance in a non-trusted domain or forest you may observe the following error:

The source machine cannot resolve the target machine, target domain or forest.

Update the hosts file on the source machine and add the following information:

• IP address to resolve target domain.
• IP address and server name of the PDC in FQDN format (or GPOADmin preferred domain controller) from the target domain. Optional you may add an additional entry specifying PDC short name as well.
• IP address and server name of the GPOADmin server instance in FQDN format from the target domain. Optional you may add an additional entry specifying server short name as well.

Connect to the target GPOADmin server instance:

• On the upper left, right-click GPOADmin, then click Connect To...
• Click New and specify the target GPOADmin server IP address.  
• Click the arrow next to Connect, then click Connect As... and specify credentials from the target domain using the Domain FQDN\username format. For example, cdch.pty.pa\japtel03
• Click Ok.

You should now be connected to the target GPOADmin server and an additional connection should be visible in the GPOADmin console as seen below: