The Technicolor TG589vac does not support DHCP Option 61 (what Sky call MER).
Most UK providers use PPP to authenticate.
Sky use a very specific protocol that most domestic routers simply don't support.
There's no way to activate MER via Putty either.
In the past you had to use wireshark to obtain your specific Option 61 username/password but that's no longer necessary.
A generic username and password can be used, but the router must support Option 61/MER.
Edit: actually it might work. Google'd this further after reading Oliver's post below.
See my other post below
Edited by j0hn83 (Sun 04-Jul-21 15:18:03)