I use my own router connected directly to my ont using cat6 cable. I also have 3 stb. This is how I did it. First you need to make sure your ont is using Ethernet to supply your internet and not the coax.
1) bridge your Fios g1100 I used the steps found here http://www.dslreports.com/forum/r31057540-Networking-HOW-TO-Bridge-G1100-So-your-Router-becomes-Prim...
2) unplug your ont box and wait for 5 min or more
3) connect YOUR routers wan port to your ont using Ethernet.
4) plug your ont in and set up your router. Note if your router isn't connecting to the internet you may need to unplug your ont again and wait 5 or more min than plug it in and reboot your router until it gets its IP address. Be patient as it can take awhile for it to get the IP address. If your still having problems you can call Verizon and have them release your IP address.
5) with coax still connected to your g1100 connect an Ethernet cable from a LAN port of YOUR router to any LAN port of the G1100. You may need to reboot your router once more after this step.
6) reboot all your stb's and make sure on demand is working. If not reboot your router once more than wait for it to find your stb's and supply them an IP address. Note make sure other devices aren't being assigned the same IP address as your G1100. I had this problem and just changed my ip range so that it would not happen again.
One more ore thing I have yet to do but am soon going to try it you can eliminate the need for the G1100 all together by purchasing an actiontec MoCa 2.0 adapter and plugging it in just like your G1100 currently is. Hope this helps you!