Your problem appears to me likely to be down to noise ingress on 275 MHz, visible as post-RS (uncorrectable) errors on the downstream, both before and after the restart. The higher number of pre-RS errors isn't materal as those are corrected on the fly, but the difference between channels confirms what the post-RS data shows. That frequency could easily be a UHF military radio system, as that frequency is commonly used for airfield comms or approach radars, but that's largely academic as the problem is not the source, but that there's a fault on VM's coax that's allowing that in as radio frequency noise.
And that's what VM need to send out a man to fix.
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks