I saw your post in my topic, so I thought I would reply here.
I posted the same Q in the bell direct forum, and was told to enter 11111 for the user id and password in the Sagemcom.
See I dont have Fibe TV so I have more testing options. You cannot disable DHCP on your modem or you will kill the Fibe TV.
This is what I am currently doing and it works fine.
I have my bell b1 and password in the Sagemcom
I have DHCP disabled on the Sagemcom
I have the wireless disabled on the Sagemcom
I have my router set to PPPOE
I have my b1 and pass in my router WAN settings
This is the end result with bypassing the Sagemcom as much as possible...
I am content as of now as long as I dont have any issues.