Move a NetWorker clients from one NetWorker Server to another

Hi we made a second NetWorker Data Zone for SAP Hana, because we are at the limit with saveset per day.

Now we have the Problem, that we can't move the NetWorker Clients to the new NetWorker Server.

We get in the Log from the client we try to backup the error

97512:savefs: Cannot access NetWorker server 'NW Server': Remote system error - Connection timed out

savefs Nw Server: failed.

we installed on one test windows client the NW Client totaly new and tried to open the Networker. When we choose the new Server we get  following: "auhentication error why = server rejected credential"

Any idea what we made wrong, and how we can solve it.

Thanks and best regards

Martin