Depends, which modem do you have?
The basic are :
Connect your PC to the modem with an ethernet cable.
Create a PPPOE connection on your PC using the standard BT username. Password can be anything.
You are aware your PC will be 'directly' on the internet so a firewall would be useful 😉
Step 1: Remove the homehub from the modem
Step2: Connect your pc/laptop into the modem using LAN1 port (LAN2 is disabled and not in use)
Step3: Open network and sharing centre on windows and click set up a new connection or network
Step4: Connect to the internet (the top option) then click make a new connection Broadband PPPoE
Step5: Username Internet@btbroadband.com and the password as broadband
Step6: connect, for some reason it may say that it cannot connect, just keep pressing try again if this happens and it will eventually connect.
Thank you for your advise. I am now able to connect Internet through Modem, in stead of through BT Hom 3.0.
Actually, I would like to change router from BT Home Hub to Cisco, but I need to setup Cisco router through modem.
Again, thank you for your kind advise.