All I can say is, "Well done Draytek!".
After suffering, as many others, with poor upload speeds on BT Infinity- compared to the BT modem- release firmware 3.6.4 finally addresses these concerns.
My upload is actually FASTER than it was witth my Huawei HG612 modem. I now get 17mb+ speeds compared to around 16mb with the BT kit.
Has anyone else tried the new firmware (available after registration from http://www.draytek.com)? It only seems to be on the international website at the moment.
By the way- turning off QoS gives me the 17mb+ speeds- it is about 1.5mb slower with it enabled on the upload

Well thanks for reporting ... you are an other one to confirm 8)
I was helping a member long time ago at TT forums (TT fibre) to set it (DHCP needs for TT instead of PPPoE with infinity)and suggested few tweaks if the upload go higher .... Lately he send me pm saying as well its upload is fixed ... so 2 from different ISP's confirming .... seems DrayTek got it right this time
As for me i have the modem but only adsl :x and it synchronizes smoother :wink:

Well Done DrayTek

EDIT

The vdsl modem has been upgraded to 1414c3... i don't know why is at the international web site only but i have looked for other models updates and is not there either the latest firmwares... so makes me think they are not using lately the FTP site

Thanks for pointing this out.

Which is the correct one for BT Infinity? There are lots of versions posted:

Vigor2850_v3.6.4__A_STD.zip
Annex A for modem code 211801 (Standard)
Vigor2850_v3.6.4__B_STD.zip
Annex B for modem code 2111112 (Standard)
Vigor2850_v3.6.4_A_2121501.zip
Annex A for modem code 2121501
Vigor2850_v3.6.4_A_2211201.zip
Annex A for modem code 2211201
Vigor2850_v3.6.4_A_232201.zip
Annex A for modem code 232201 (recommended for UK-SEG only)
Vigor2850_v3.6.4_A_2431301.zip
Annex A for modem code 2431301
Vigor2850_v3.6.4_A_243601.zip
Annex A for modem code 243601
Vigor2850_v3.6.4_A_243701.zip
Annex A for modem code 243701
Vigor2850_v3.6.4_A_244001.zip
Annex A for modem code 244001
Vigor2850_v3.6.4_A_2471201.zip
Annex A for modem code 2471201
Vigor2850_v3.6.4_B_2111302.zip
Annex B for modem code 2111302 (recommended for Czech only)
Vigor2850_v3.6.4_B_2111312.zip
Annex B for modem code 2111312
Vigor2850_v3.6.4_B_2121302.zip
Annex B for modem code 2121302 (recommended for Slovakia only)
Vigor2850_v3.6.4_B_214702.zip
Annex B for modem code 214702
Vigor2850_v3.6.4_B_215202.zip
Annex B for modem code 215202
Vigor2850_v3.6.4_B_246302.zip
Annex B for modem code 246302

Any help would be appreciated in selecting the correct download.

Thanks.

I am presently running Vigor2850_v3.6.4_A_2471201.zip
I originally tried the UK/SEG one and then the above, but did not notice any difference.
Have fun!

Thanks for the quick reply. Much appreciated! I'll give it a go.

Edit.

Well, that's a big improvement over the old FW. I had reverted to using the BT modem as the speeds were significantly better than the 2850.

With the new FW and the line connected to the 2850 I'm getting about 2mbps improvement in DL (75Mbps) and a 1-2Mbps improvement in UL (>17Mbps) - both these figures are referenced to the BT modem. I can happily put the BT modem in the garage now. Cheers!

Glad it's worked for you too.
I would thoroughly recommend any 2850 users to try the 3.6.4 firmware on BT Infinity and similar lines. If you do- post your results and give the thumbs up to Draytek