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..