This is a typical graph from one of the connections:-
I can not see an example like this in the FAQ. Can anybody point me in the right direction to look for the cause. Rebooting the router seems to put things right for a short while (as can be seen by the re-boot about 20 minutes ago, which stopped the packet loss).
Line One:- Zen - DrayTek Vigor 2600VG
Line Two:- EntaNet (Aquiss) - DrayTek Vigor 2600