<<< And the router wants me to connect a Enet cable from the router to the modem >>>>
That suggests that you have a "Cable/DSL" router suitable for use with Virgin's *CABLE* broadband service, where the router does connect by ethernet to the Cable Modem.
With ADSL via the phone line, you need a *COMBINED* "Router & ADSL Modem" which replaces a USB Modem.
If you do in fact have *CABLE*, then you need to follow the correct procedure when swapping the connection to the Cable Modem. Instructions click here