I know the 7800N EWAN Port is 100Mb BTW
OK So here is my problem/question...
I have had a Billion 7800N now for over a year now was once running on O2 ADSL2+ LLU (UK) internet getting decent results from the 7800N (better then any other router) then when we could FINALY get Fibre Broadband we swapped to BT Infinity (UK) ... up to 40Mb Download and up to 10Mb Upload.
BT EchoLife HG612 (VDSL) Modem conenct on its LAN1 to the EWAN port of the Billion 7800N (using CAT5e) Conenction method PPPoE using Firmware 1.06f.dc1 (havent yet flashed the test firmware that fixes sky's connections)
Back on topic i was getting great results between 30 to 37Mb download and around 6 to 8Mb Upload (test done using Speedtest.net).
AS of yesterday BT have now rearranged there speed Packages and i have now opted for the Up to 76MB !! Download and Up to 19MB !! Upload
now yes this change has only just happened and i know they have to monitor and tweak things. BUT now my Speed Results we are only seeing a max of 39MB Download and 16Mb Upload ...
the UPLOAD isnt a problem thats awesome the problem is i dont see any speeds going above 39MB and as ther is a previous post about max 34Mb throughput on EWAN...
I WOULD LIKE AN OFFICAL ANSWER is this a Firmware Issue?? or a Hardware Limitaion?? ... meaning do i now have to start looking for a New ROUTER !

BTW as i am at work i cant test further i m going to try plugging my pc direct into the BT EchoLife Modem and speed test to see ... then again back into the 7800N then i will also try flash the test firmware for sky connection fixes and test.
PS i know its not my PC as a Core i7 920 with 12gb ram, 120gb sata3 SSD, with onboard Marvel or a Bigfoot Killer 2100 NIC aint no Slow Poke.
PS2 Have ordered some CAT6 cables not that that should realy do much difference but hey cable is cheap so worth a try