Hi
Thought I'd give you an update, hopefully this may help others with similar issues..
HDU returned, eBay guy message me a few days later saying the connector was not seated correctly..
Anyway, had a PM and they recommended a Asheridge AS-4p 4 port powered splitter, I thought for £15 you can't go wrong.. The parcel arrived splitter and power plug, you have to make your own power lead to connect the plug and splitter using the F-Type connector and you also need to buy a female coaxial connector also for the VM feed in.
After a short while my internet and two Vermin boxes are working fine..
SNR is 47
AGC is 71
I don't know how good that is, but the picture is fine and no buffering..
Thanks all..