Problem with USB-Serial on Windows 7

I've setup a VirtualHere server that's working fine with a Windows 10 machine. But when I try to use it on Windows 7, here is what I observe:

- The Server running on a RaspberryPi3 iLinux OS gets detected - AutoFindHubs is turned Off and I have specified the Server IP.
- 2 out of 3 devices connected to the RaspberryPi show up in the drop down in the Client running on Win7
-- Mouse - detected
--Keyboard - detected
-- USB-Serial FTDI device - Not Detected

- The Client running on Win7 also runs Symantec Anti-Virus and VPN software.

- Client and Server are on different networks.

Also, the 2 devices that are detected(Mouse/Kbd) keep appearing and disappearing in the Client. Sometimes the Client just dies.

I know the Server is working fine as all 3 devices are detected and the VirtualHere Client works fine on a Win10 device.

One thing different is that the Win10 Client that works fine is on the same n/w as the Server+RaspberryPi. The Win7 Client that has problems runs on a different n/w.

I have also tested the USB-Serial directly(physical connection without VirtualHere) on the Win7 Laptop and it worked fine.

What could be the problem with the Win7 VirtualHere Client - some kind of AntiVirus/Network/Firewall issue? Any help/suggestions are welcome.