The BT Home Hub 5 - Type A is one of the few routers that can run OpenWRT (https://openwrt.org/toh/bt/homehub_v5a) and has a VDSL modem built in.  Reportedly good 11ac wifi too.

I bought one off ebay thinking I'd get around to flashing OpenWRT on it.  But I never got further than taking the front plastic casing off.

$10 including shipping and it's yours.