uname -n on Host-B shows the name as LANSvr which is correct.
I had previously scanned Host-B but you prompted me to check it again and I found in the Home/.nx directory references to FileSvr for the local system. So I used Synaptic to remove NoMachine and deleted the .nx from Home and then reinstalled NoMachine.
Now all is working correctly. I must have made a mistake somewhere along the line.
Thanks for pushing me over the line to get my mistake fixed.