Keith
I have found the problem, thanks for your help. I thought I should post this incase other early adopters of the new beonet system see similar problems.
I have found that out of 7 b&o product cables ml-rj45 supplied I have 2 faulty cables.
The cable causing the problem described in this thread, once I checked it with a continuity tester i found a wire shorting to the shielding. I traced that to a fault at the rj45 end of the cable. As this cable is already buried in the wall ducting as it goes from my cat7 plate to the bv10, i cut the rj45 end off as its more likly the fault is in the termination than the cable. I found the fault in the rj45 termination.
But the reason for the post was to expain what I found, the product cable has some bespoke work done at the rj45 end, at the ml end there are 9 wires connected out of the 16ways at the rj45 end there are 8, the ninth being solder jointed pink to white blue and then these go to pin 3 on the rj45. The joint is covered with heat shrink tube but it was this that was faulty and shorting to the shield. Ive now re done this joint and put a new shielded rj45 on and all is now good.
Id suggest that these cables are likly to be fairly unreliable because of the soldering as they are clearly manually made up. The other faulty cable I have is clearly a similar problem, it just did not work at all, now I know the pin out, it is again pin 3 on the rj45 that is not connected at all so obviously there is a fault on the soldering on this cable as well.
Just as a suggestion to the forum, anyone using these ml-rj45 cables intending to hide them in the building fabic or seeing problem as i have had I suggest they are fully tested first, not just by plugging 2 products together but by continuity testing end to end and each of the rj45 pins to the shield.
regards
peter