given that vdsl is supposedly backward compatible to adsl / adsl2 etc, what would happen if an adsl2 modem were plugged in instead ?

Pass, have seen ADSL2+ producing sync on a VDSL modem, but no PPP on the router, could this be PPPoA/E different VPI/VCI settings ?

Easy.. it wouldn't work

given that vdsl is supposedly backward compatible to adsl / adsl2 etc, what would happen if an adsl2 modem were plugged in instead ?

It might be able sync up at the dsl level but as ADSL modems are expecting ATM and the remote end is expecting Ethernet frames I doubt that much else would happen.

I'm running a Fritz!Box 7390 VDSL2 modem/router for my ADSL2+ connection to Sky, but I'm not sure it would work the other way round.

BT are on the 2nd version modems now (2V) which should be more reliable.

However if you want a business class VDSL router then how about a Cisco 877VA

http://www.broadbandbuyer.co.uk/Shop/ShopDetail.asp?...

Correct it will be the other setting that control authentication handshaking that are the issue, the physical xDSL transport layer should work

In reply to a post by Zarjaz:

What's wrong with the Modem; ok, it's unreliable (on my second one),

To this end, they are now shipping version 2 modems, the fault on the originals have been traced to the goo beneath the heat sink(sic) not being thick enough and causing the overheating problems.

That said, mine has run fault free since last November, the secret being having it mounted upright.

That is a poor excuse - the thermal grease should be as THIN as possible to get the maximum transfer of heat. With a flat ceramic chip and smooth heatsink it is only required to fill the minor imperfections in the two surfaces.

That is a poor excuse - the thermal grease should be as THIN as possible to get the maximum transfer of heat. With a flat ceramic chip and smooth heatsink it is only required to fill the minor imperfections in the two surfaces.

I agree absolutely; however, I've also heard the "grease not thick enough" excuse when what was really meant was that the grease was simply the wrong stuff. I've no idea what's used in the modems, but some years ago I came across CPU failures in high-end servers due to overheating arising from grease issues. The spec of the grease had to be something containing heavy metals for greater thermal conductivity.

Unpleasant smells - not necessarily the usual smell of burning - were a common symptom.

Also, I think silk screen application helped to eliminate the erroneous "slap plenty on" mentality.

Dave

One using carbon are the best - there are some compounds which have diamond dust in them! The metal based ones using elements such as silver, copper and aluminium are a lot better than the ceramic based ones too.