You said your friend's FiOS connection did not reproduce problem. Is he on coax or cat5? And what version of Actiontec does he have?
Since you indicate the download completes instead of stalling or timing out, do you have a byte count or file size you know is accurate? »askville.amazon.com/Downloading- ··· d=625358
suggests saving to the C: drive instead of a secondary drive, and suggests an ISP cache may be at fault and recommends a different port than 80. There is a download manager recommended by one person there. I have no idea how effective it might be over built in systems.
Otherwise, switching to cat5 and running wired directly to the ONT sounds like it would eliminate MoCA connection and Actiontec as the problem source.
To get a replacement router, exchange it at your local FiOS store. You might want to call first. I was in my local store where they said they didn't have any problems exchanging routers. However, they only had Rev.E on hand. If you call tech support and say your router isn't working (just don't tell them it's because you unplugged the power cord), they will send another one. Some people might say that's cheating the system, but I say if you have really eliminated all possibilities other than the router, then sometimes you have to tell the chat bots what they need to hear.