Hello,
Please look into /nsr/res/servers file to make sure that your new test 
server is defined ( on the client).
Are there any firewall, ip tables, special configurations that could 
effect the backup from the new server, can you resolve the clients host 
name from the server ?
lastly, try running the client backup from the server with more verbose 
logging to generate specific error that might point what's wrong.
HTH

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