Client error -519 network communication failed

[Marietta]

I'm having problems with clients not being connected sometimes and getting error -519, network communication failed. We all have a fixed IP address. I am running Retrospect version 8.1 build 626 on an Imac OS10.6.3. Client version - 6.3.027 . Half the time, retrospect cannot connect to some of the clients, another day, it can't connect to others. If I do a test by address, the clients show up, but usually they don't when searching by multicast (sometimes they do if I restart the retrospect engine). I usually find out if they are connected properly after the backup (successful or not)

Is there an easy way to verify that the clients are connected properly? And how would I connect them, if they are not? Right now, they seem to be connected but I get the communication error.

 

One thing I noticed when looking at sources: If I highlight one of the clients or sources, down below under details - summary, they sometimes have the wrong IP address listed. This does not seem to correspond to the ones that are not being connected though.

 

I am not very familiar with DHCP setups, and am hoping I do not have to become an expert with them. I think that everything should be set up properly for backups. They worked fine for a while, and we haven't changed anything. The firewall port is allowing retrospect through.