Windows Firewall is turned off on the Pro m/c. It has Kaspersky Internet Security with a firewall but I disabled that to no effect. One of the laptops also has Kaspersky and the other has Malware Bytes. I disabled all of it for just long enough to run a test. No luck.
The 'remote machine for the internet test was a Mac. The symptom there was intermittently getting a ‘Performer’ red sync light when on playback and immediately every time I tried to record, whatever I did with stream speeds.
With the big machine running SE and a laptop tethered to my iPhone I got exactly the same symptoms. Connection speed from the tethered laptop was 16.3 Mb/s down and 12.7 Mb/s up.
My idea was to run the LAN test to prove conclusively that the issue was with the ‘Pro’ machine. I so want it to work and I will certainly buy the Pro licence if it does, but I’ve been frustrated at every step with this.