UrBackup 2.4.12, Windows 7 and WiFi - Bad combination

This is a strange issue that occurred after I upgraded my backup servers (2) from 2.3.8 to 2.4.12

One server is Windows 7, the other is windows 8.1. The clients are on ethernet or wifi, so the servers are on both networks. Prior to upgrade, each server could see and backup all clients.

After the upgrade, the Windows 8.1 server can see and backup all clients.
The windows 7 server cannot see the WiFi clients. Clients are 3xwindows 10, 1xWindows 8.1, 1xWindows 7

I’ve not been able to find a work around for this, other than physically connecting a wifi only laptop into the wired ethernet. This is not a practical solution.

I’ve turned the firewall off and checked that the WiFi is private network, but nothing works if the windows 7 backup server is trying to connect via wifi.

Something has changed between 2.3.8 and 2.4.12, but I’m at a loss now as to what to do.

Does anyone have any suggestions?