Just an update. The serial numbers have been matched and unfortunately I am still without broadband for over 3 weeks now.
Frustratingly no one has any answers.
Is there anything left I can try to do? I been on the phone had engineers come out, but all they do is say that the lights are on so everything is working, the problem is between the ONT and router. But it can't be because I been sent different routers, tried third part ones, different cables, nothing has worked.
Any help would be appreciated.
Is there anything in the router logs re PPPoE authentication? From what you have said, it looks like the physical layer is up, but no PPP session started.