The last couple times I have had to move a UrBackup server to a different device I have disabled the service, installed UrBackup on a new server and then attempted to create new client installers for those systems that used to point to the old server.
More often then not I end up having to uninstall and reinstall several times before the client discovers the new server and starts using it. Specifically this has happened on a exchange server I manage.
Is there a process for completely wiping out the old client because it seems like the uninstaller doesn’t do it - it seems to lead to problems.
It seems that renaming the client from Exchange to EmailServer did the job. 
Yes re-using names for clients is bad.
What do you mean re-using names for clients is bad? I have one client that will not connect to my new URBackup server, even after re-installing the client numerous times. I can’t change the server name since it is a critical file server. On the URBackup web interface, choosing “download client for windows” only shows the existing servers that are backing up.
Well in my case I have an agent called Exchange I made a new Agent called Exchange2 and after that it work. I had previously uninstalled and installed many times.
Sorry, but I’m still confused. What do you mean “made a new agent”? Did you change the name of your server?