Hi, I just put in the username and password and it worked off the bat. That was on my old FritzBox. I upgraded to an Asus AC-86U, and same thing, just put in the username and password.
Assuming they switched your Hey router for an ONT, they may not have commissioned the ONT properly.
Does it have all 3 lights lit up solid green?
Hey!Broadband 1Gb Fibre
Asus AC86U - Asuswrt Merlin