Synchronisation failure is where the hub can't maintain a lock on one or more of the 28 channels it uses to connect with the gear in the street cabinet. And when it does lose synch, that loss of one or more channels becomes a "partial service". What that means for the customer is slowdowns, disconnection and poor latency. The hub does try and renegotiate the lost channel, but that takes time, and the problem will recur.
The underlying cause is usually noise on the upstream, because it is those channels that the hub uses to communicate with the gear in the street cabinet. The upstream looks OK on the data you've posted, but that's most likely because you've recently rebooted the hub (I can tell that from the low error counts). Rebooting causes the hub to renegotiate all 28 channels, and usually provides a temporary fix, but because the underlying cause isn't fixed, it will recur. Replacing the hub won't make a blind bit of difference - that's a cheap fix by agents who know nothing about the technology. If they'd looked at your network log and knew what it meant they'd have sent out a technician to find the real problem.
You can try dialling it in, but chances are you'll get more of a run around by the utter clowns that VM use as offshore technical support. Better to wait (maybe a day or two) for the UK based VM forum staff to get round to this post and advise on next steps. They're usually very helpful, but don't accept the excuse "I've had a look and everything appears OK from our side" - the Network log is crystal clear on the fault and the impact on your service, and that's been recorded by VM's own equipment. You need a technician.
