Any vdsl modem that works in bridge mode should work but the issue is if your asus could run merlin firmwarw its very straight forward to configure for
If I went for a Draytek modem, would I need to configure the ASUS for Sky? Or would it just work? Considering buying a new router, but think I'd still
Option 1 sounds like something that's doable now - I think all I'd have to do is set the ASUS to AP mode? Currently it's "wireless router mode".
Don't think that model supports merlin (would make it easier to configure for sky)..
Sounds like you've got the ASUS doing L3 routing as well (so double NAT with IPv4?). Sadly the Sky Hub doesn't support sub-delegation of IPv6 prefixes