I have two BT Humax 2100 boxes and both suddenly refuse to connect to the router. I am using TP-Link 200 Mbps ethernet connectors. I have tested the setup on my Tower Sytem computer and all is good yet when I plug the same cable into my BT box it doesn't connect. I am in amess now as, having done both software and factory resets it still doesn't connect and hence the setup sequence hangs asking for connection to the router. So now I cannot watch Netflix and such nor record programs since the setup hangs. I've tried Humax support but, after saying they do not make a 2100 (???) just keep saying contact BT. I've tried this but get no response. Any suggestions, other than bin both units, would be helpful. Thanks.
In these circumstances, I would do a flight of reboots, from router to YouView box, one at a time, starting with them all powered off, and letting each settle before moving on to the next:-
Router
PLA nearest the router
PLA nearest the YouView box
YouView box (do a Maintenance Mode 2)
https://support.youview.com/youview-box/box-and-remote/using-maintenance-mode/
I'm not clear how the second YouView box is connected - a further Ethernet cable from the PLA? - but leave it out of the equation until you get one working.
If still no go, try to bypass the PLAs, either by using a long Ethernet cable from router to YouView box for test purposes, or by moving the YouView box (and a TV!) to near the router where you can connect them with the existing Ethernet cable to the first PLA, (though this may not be feasible, of course).
There’s no reason why T2100s should have stopped working - I’m watching the BBC News on a very similar T2110 right now - but EE and BT will only support boxes on a current subscription, which I’m guessing you do not have. (And if you do, ask them for the current Pro box, as a replacement for one of your T2100s).
But plenty of advice available here, as above.