Over the last few days my Fios download speeds have been in the range of 2-8 Mbps, using Verizons speed test. I have rebooted both my computer and router but nothing seemed to help. I contacted Verizon support via chat and they tried somethings from their end, but again no change. The Verizon rep then pointed out that I have an old router and that upgrading (for an additional $10/month) MIGHT help. I am located in Manhattan, across the street from a Verizon switching center and have 25/25 internet plan. Speeds in the recent past have been MUCH higher, and I cannot believe that the problem is with the router (actiontec MI424WR v1.) The router is connected via ethernet cable to my pc.
It could be the router, wiring, or the ONT. Do you have an WAN ethernet connection? You can try plugging into your computer directly and see what speeds you get to see if the router or ONT is the problem.