I have just bought a new laptop, wifi6 enabled. I bought a Tp Link Archer Ax 50 Router for wifi6 function and because this has no built-in modem, a Vigor130 modem as well. Everything functioned perfectly until I noticed that my recordings of World Cup Biathlon on Eurosport had failed. I have been recording this for years successfully on my Plusnet Youview box. I phoned Plusnet TV technical help and was advised to ensure that Multicast was enabled in the router, as many routers have a disabled default. I checked and discovered that it was already enabled. I phoned again and was advised to do a factory reset of the Youview box (avoiding deletion of recordings). I did this to no avail. I was then told to repeat this but choosing the option to delete the recordings. I decided that this was unlikely to succeed so didn't. I phoned yet again. By now I was completely sick of Christmas carols and never wanted to hear one again. The lady I spoke to told me that I wasn't entitled to Eurosport. We had words. I checked my entitlement and phoned back. I was listened to sympathetically but then left on hold for half an hour until the phone was answered again by the same lady as the day before and it was agreed that I am entitled to Eurosport, but no solution was suggested.
After considerable searching, the solution was found on a TpLink forum thread. The modem needs to be set into Bridge Mode. This ensures that the signal passes to the router without processing by the modem. I followed the instruction on a follow-up post to make this reconfiguration.....and bingo, after rebooting, the Youview box gave me Eurosport perfectly.
I have a feeling that this would apply equally to problems with BT Sport but I don't subscribe to that.
The posts that solved my problem are at the following links: