I have searched this forum and have found a number of similar issues but nothing that seems to quite match my own experience so apologies if the solution is already out there.
I have just switched to Virgin fibre from BT infinity and have a Virgin Media Hub 3.0. and Apple Extreme. I have put the hub into modem mode but cannot find a config on the Extreme which will allow it to connect to the hub, I have tried DHCP but mostly the APX does not connect or seem to find the IP address of the hub.
I have been playing at this for hours and getting nowhere please have you any ideas. I had the Extreme working very satisfactorily with at BT supplied dsl modem but using in this case PPPoE and it worked fine. I believe it is not possible to use PPPoE with Virgin
Late last night I got it working. The only thing I did differently was to change the DNS to Google, 126.96.36.199 and 188.8.131.52 and try different rebooting cycles and updates on the APX, I eventually got the APX to recognise the IP address of the VM Hub by repeatedly inserting the wan cable into the VM box and then doing another update, to my surprise it all suddenly came up smiling.
So final settings were DHCP and DHCP and Nat for the local network. All seems to work fine with no errors reported and a nominal 50MBS up and 3 down.
It was a long hard road!!!!
The Airport Utility was 6.3.7 and the Airport Extreme is the tall rounded square one from Nov 2014.
I definitely had DNS settings in the APX but I changed them to a forum contributors recommendations and it worked. Unfortunately I dont seem to have a record of what they originally were, I know that they were probable Namebench recommendations as I usually do a nambebench check about every six months. I do not think the APX was using BT DNS but it maybe the answer, bloody frustrating time though and thanks for your contribution.
For anyone following this I have since successfully changed the DNS settings again in the APX to the latest Namebench results with no ill effects on the service or the APX. Hopefully that is now ...that.