ok the issue continued through the night - and no answer at all from Virgin Chat.
So this morning I decided to "BIG 60+ sec reset" the hub.
First with PC on - different MAC on PC gave different IP post reset (vs old IP via Router) - no problems !!
Then in with the Router Cable, REBOOT the Hub (important) - then check Router - and back to same IP.
But NOW - NO ISSUES with packet loss - 0% PACKET LOSS.
Then I checked HUB Firmware since the "light" was back to white and not green:
Hub 4: Software Version - 01.02.065.21.EURO.PC20
which is a far cry from the version it updated to in 3 days ago when the issues started.
So my best guess now - and seemingly confirmed - is that the new firmware sent out to my device 3 days ago is the culprit of the massive packet loss that forced my routers interface to drop the connection and switch to backup every 2 minutes.
Now I'm just REALLY nervous that Virgin will ship the same firmware out again overnight - infusing massive packet loss again. But since it is IMPOSSIBLE to talk to them - I have NO idea on how to warn them about the issue. Worst case I'll do a "big reset" again tomorrow....