said by guppy_fish:
Run a simple test, no guessing needed.
Directly connect your computer to the ONT perform the upload, if it works or not, then since you imply it fails every-time with a large upload, this should answer you question if its the router or not
Sorry for the delay, I finally got around to testing this.
I released the DHCP (as per suggestion from "More Fiber"), unplugged the router and then went to the ONT.
I noticed that the MoCA light was blinking red
Anyway, I plugged in my computer directly to the ONT via Cat5 cable - however it wouldn't connect.
When I plugged my router back in, the internet worked and the MoCA turned green. I tried to transfer a coule of files (the old way - i.e. not directly to the ONT) and it crashed during the 2nd transfer.
Did I do something wrong with the ONT connection?
I found someone else with a similar problem
but don't see that he got it resolved only that he also had about 10 FIOS techs come to his house without fixing it