For weeks now I have been suffering with intermittent loss of broadband. There doesn't appear to be any obvious event to trigger them and it affects all devices through both wired and wireless connection multiple times each day (usually 2/3/4 times throughout the day).
It happens throughout the day. I am on work calls and suddenly I lose connection. There are times I lose connection for an hour at a time. Every day!
Well, you've already confirmed that it happens when connected via a cable, which is usually the first thing to check.. so next steps are;
can you set up a BQM - once set up, find the Live Graph and click "Create Sharing Link" - post that back here.
Next, browse to your hub on http://192.168.0.1 - don't log in, click Router Status - copy/paste the tables from the Upstream, Downstream and Network Log tabs back to this thread - you'll need multiple posts for this, the info wont all fit into a single one..