Add a fake entry in your hosts table so that the hostname can be resolved to an ip. Then restore the files via a standard directed recovery.

Hi Aegh,
I would have performed the following steps:
1) delete the old client "Server1.abc.com"
2) create the new client "server1.external.abc.com", paying attention to recreate a new client-id
In the new client add the old resolutions "Server1.abc.com" in the tab aliases
3) rebuild the indexes of the new client with the command "nsrck -L 7 server1.external.abc.com"

This should allow the association of the old hostname to the new hostname and thus allow the restore without further problems.

Otherwise in the restore command you force the name of the old client recover -s bck_srv -c Old_client_name ....
 

You can even use another method: nsrclientfix 

However, before you do this, may I strongly recommend that you use another small test client to verify the behavior to familiarize a little bit with the procedure.

Thanks all for the replies, much appreciated!