I WAS WRONG!
Eventually, I tried running TrainerRoad and Rouvy without the convoluted network configuration. Specifically, I removed the parts that were forwarding my USB ports to the cloud computer, but ran the applications locally, instead. Those parts were the peer-to-peer VPN by ZeroTier, and the USB server by VirtualHere. Without those two services in the mix, TrainerRoad and Rouvy played nicely together – without any apparent interference. In other words, runninng the applications locally obviated the port fforwarding hack and elimiiinated whatever the problem was being caused when running TrainerRoad and Rouvy together.
The performance of TrainerRoad and Rouvy on the Hewlett-Packard EliteBook 840 is adequate, but not optimal. Eventually, I’m hoping to rectify that with an upgrade.
In the meantime, I do have one niggling issue with the EliteBook. The system seems to be having a problem loading the driver(s) for the (Dynastream Innovations) ANT USB stick. Oddly, if I use the aforementioned VirtualHere client/server on the local system, the problem goes away. Perhaps remnants of the VirtualHere stuff is interfering with Windows own device management services.