Each firmware (STD/Vector) have an alternative modem code at wan>general setup>dsl modem code
See if is better by changing them
I think Draytek should have some more alternative modem codes
The 2820/2830/2850 had much more available modem codes

Hi babis3g,

Each firmware for the 2860 has two different DSL Modem codes, and I have tried all of them (six in total).
For the VECTOR firmware, all four modem codes dropped the connection.
For the STD firmware, both AnnexA_548006_544401 and AnnedA_560816_552011 are stable, but both get the same (lower than vector) sync speed.

I have also tried setting SRA to 2 in a bid to resolve the dropping connection on the vector firmware.

So I think Draytek needs to go and work on the stability issue for the vector firmware, particularly in relation to Infineon equipment, since a few people seem to have reported this.

ok thanks for your effort testing
Perhaps the dsl drivers of the vector are too aggressive for higher speed but less stable connection
Yes hope draytek looking this thread so they can work out some more modem codes

This document should answer some of the question surrounding configuration questions on VDSL:
http://www.sinet.bt.com/sinet/SINs/pdf/498v6p0.pdf

I understand all FTTC in the UK is ultimately supplied by BT / Openreach, so this would apply universally, whichever provider the service comes from.

Further to above, I have set SRA now to manual (1), which removed some more instability.

Needless to say, the DLM didn't take the experimenting and buggy Vector firmware kindly, so I'm now both interleaved an on reduced speed.
I understand this improves after 10 days of continuous connection, but I don't think I have ever managed 10 days of uninterrupted connection on the Vigor (even on ADSL), so have plugged the BT Modem in for the time being.