Have successfully connect to the Sky BB network with Vigor 120 and using a laptop can reach speeds of 15.6 mbps download against speedtest.net however, when I replace the laptop with a connection from the 2910 (WAN1) speed through put is down to 4 mbps. Looking for any advice or clue as to what may be causing the change.

Background:
Previous configuration was Draytek 2910 supporting on WAN1 a Vigor 120 connected to O2 network (Static IP) config and through put about 15 mbps against speedtest.net - in addition WAN2 was (and still is) supporting a Vigor 100 to BE network (Static IP) config and though put is up to 16 mbps. Been this way for ages and all very stable. Wanted to access the Sky network for "Anytime plus" so switched the O2 connection.

Having spent 15 days getting Sky to resolve faulty exchange equipment now get a respectable 15 mbps connection with the Sky router, swapped in the Vigor 120 and same speeds achieved with same laptop. I can also see the ADSL2+ stats are clean and Vigor 120 is syncing at over 17.5 mbps down and more than 1 mbps up. Unplugged laptop and plugged in the WAN2 Draytek 2910 connection and through put drops like a stone (as if the connection was not at ADSL2+ speeds).

This is first time using PPOE to PPOA config and wonder if there is an issue I may have missed.

I know that the 120, out of the box, has to be adjusted VPI 0 and VCI 101 and changed to MPoA instead of PPPoA etc. ( full detail here: http://www.draytek.co.uk/support/kb_vigor100_setup.html )

Could it be that the unit needs putting back to 0 / 38 and PPPoA ? While you're checking, it is worth ensuring the unit is on the latest firmware.

Regards, Neal

Neal, thanks for the response but if the settings had changed then no connection would have been made. There is a resolution to the issue detailed next.
As I was totally unable to view the Vigor120 when it was in the loop with the Dratek 2910 (and that was the only config where it would not work at expected speeds) I assumed the issue was not going to be resolved with the 2910 in play. It is "old" kit and running on the latest firmware so unless there was a config error I was flogging a dead horse.

Enter Draytek 2850Vn from stage right. Why 2850Vn well I am just waiting for my exchange to go FTTC and I will switch to that connect at the speed of light. 2850Vn also supports ADSL2+ and I can see what is going on so installed and configured the router - works like a dream, syncs at almost a mb faster than the Sky supplied SAGMCOM router on download and and a quicker sync speed on upload (about 20% faster).

So in short the website that extracts the Sky password from the Sky router works well, the later Draytek kit works well and I can enjoy best of both worlds, good configurable router, pretty quick SkyBB for the kids and the Sky box that is not going to interfere with my connection for work and I have resilience with two ADSL circuits from different suppliers with a third option if all else fails using a USB modem on the GSM Mobile network.

Going to configure the rest of the set up (all my VPN circuits etc - shame no export and migration) but how often will I be migrating routers - not that often looking at the nice new 2850...