Looks like you hit the nail on the head with your first answer. QOS was set to 20Mbs Down and 2Mbs up. I think I set this thinking it was the limit per device for some six devices on my network....

Since I upgraded to the latest firmware version for my Deco M4R connected to a Virgin Superhub 3 in Modem mode I have been having issues with bandwidth on the Decos. The best I can get is 20Mbs down...