Your downstream power levels are two low on a few channels, the upstream power levels would have been useful.
The logs are showing quite a few T3 errors and some T4 errors indicating the connection dropping between the hub and VM servers.
You could give the coax cable between the hub and the cable entry point for obvious signs of damage and all connectors are hand tight.
You will need to contact VM for resolution, either by waiting here about a week until a VM Forum Team Member picks up the thread, or give them a call on 150 from a VM line or 0345 454 1111 for a quicker response.
Yes it was fitted by a VM engineer sometime ago to rectify a previous issue when I had an earlier version of the superhub. Its connected to the incoming feed which then goes into a splitter, shall I remove it?
15dB attenuator!!!!! wooooooow... Your engineers must be as good as our engineers, he must have grabbed the first one out of his pocket and rammed it on.
You need a 6dB attenuator fitted to bring them levels back down to being nice, 15 is just WAY to big... you can either wait for forum team to pick this thread up in a week or so who will book you an engineer out to fit one (good luck on him fitting the correct size).. Or you can buy them on ebay for a couple quid and fit it yourself.(remember you need a forward path one if you do)
Last night router re-booted every 10 mins so I connected 15db attenuator again and service has been a bit more stable tonight. I've ordered a 6db attenuator from your ebay link, so I'm hoping it will make a difference when it arrives