Thanks for the quick response.
I have not been able to find any updated drivers
for the Huawei modem - and suspect that this may be the main cause of the problems I'm having.
I did find that removing and then reinstalling the Huawei drivers fixed the SonicWall VPN connection. This is now working normally again (so long as I don't even start the Cisco service).
I have not been able to get the Cisco VPN to work at all - BSOD every time - but I think I'm going to give up on that for now. It works fine with a regular wifi connection, but not with the Huawei modem, again pointing to the modem driver
as the source of the problem. This will have to wait until I can get updated software for the modem.
As far as the VPN clients are concerned I realize that the network devices are disabled - this is normal, they are enabled by the VPN client software when a connection is initalized. With the exception of the Huawei device, I have not had any problems having all of these VPN devices installed concurrently.