After going through the same disappointing experience as others. I decided just to downgrade my plan. I was hoping to get significant performance increase from my 300/300 plan, but I do not. Using Verizon's speed test and independent ones, the max I have seen is around 500 using ethernet directly connected to the ONT but typically it remains in the 300 range.
Others can try and argue the technicalities, of "up to" or the ONT gets 1gb. Well that does me no good. So I am not going to pay extra for no increase in performance.