HyppTV is on a different VLAN with Internet so it will be either LAN connectivity with Internet VLAN or HyppTV VLAN.

I suggest you try Powerline first, I manage to get around 50Mbps on a good day with Powerline even on different phase.

This can be done, for example with Mikrotik routers. You'll have 1 Mikrotik router in the study which is configured to trunk both vlan500(internet) and vlan600(hypptv) over a network interface to the Mikrotik router in the living room. The network interface can be either a cable or wireless. I'm doing something like this but with a cable, trunking vlan50 (LAN traffic) and vlan600 from room upstairs (where BTU & router is) to living room downstairs (AP & STB). Another example is my auntie's house where she's trunking only vlan600 over wifi. Here she uses a (illegal) frequency out of the normal channels 1-13 to avoid interference.

One thing about HyppTV streams and wifi is that it's very sensitive. You'll need a good and consistent wifi connection. If not, you'll start getting buffering or loss of signal and it takes ages to re-sync.

I have yet to try the latest TP-LINK repeaters but the old ones are pretty good. I think you can try the RE200

D-Link is decent and it is cheaper but there's no mobile apps support.