Try connecting the BT hub to your switch using your long lead and your TV and PS4 to the switch and see if both work OK in that situation at the same time
From what I can gather, your issue could be the powerline or your ethernet switch and we need to remove one from the equation
If your Ethernet switch is in fact a hub/router, then I think that will also have a conflict with the BT hub, you only want one router on the network. A simple switch will be better
Sorry if sounds confusing. I only have 1 router, and 1 ethernet switch.
I've tried the powerline only with no ethernet switch (as my powerline has 2 sockets), with the BT TV and PS4 and same. either the TV didnt get channels and/or the PS4 speed was 1Mbps
We want to try the other way around
Bypass the power line using your cable. So, connect your BT hub to your switch using your cable and then both TV and PS to the switch. If this works, your power line is the problem
Is the powerline adapter connected direct to you BT box, or is it via a ethernet switch?
I found something today. I have been given a LED lighting unit for an aquarium. Soon as I switched it on, I lost the broadband over the powerline, with the LED light in the same wall socket as the powerline
It was cured by moving the light to another 13A wall socket
You might be seeing something similar and the newer powerlines are just less susceptible to EMC noise on your mains supply