So I just got off the phone with Verizon Fios Support. I was only getting speeds of 9+ Mbps and not the 15Mbps that they advertised. It turns out that my DI-624 wireless router can't get up to the 15Mbps speeds, because we tested the router they supplied, a VDI-604 wired router, and got over 15Mbps. So I was told that Verizon has a version of the DI-624, which they label VDI-624 (V for Verizon, I guess) that would get me to the advertised speed.
This sucks, of course, because i really don't want to drop the extra bucks for Verizon's version of my router. Has anyone experienced this, and/or have a workaround so I don't have to shell more cash for something that should have been at least fine printed in all the Fios ads I received.
Thanks.