Not a problem more a solution. I can see folks from other ISPs have hit this, but I don't have logins to report the fix on.
The Problem.
Despite having a 40Mbps connection, my 4K TV only streamed Netflix at a ridiculously low resolution .
The Fix (after a half day with wireshark & lots to twiddling and re-cabling, changing MTU etc) was . The Firewall->defense setup-> Enable UDP flood defense (turn it off, or set the limit higher) . Turns out 2000 UDP packets/sec is not enough to do 4K TV ...who'd thought?
