If you have Verizon set-top-boxes, the router must be connected to coax. The router creates a LAN on the coax so the set-top-boxes can connect to the internet for guide data, video on demand and more.
You can use Ethernet from the ONT to the router for the WAN connection. This is needed for speeds of 100Mbps or more. It still needs to be connected to coax to create the LAN for the set-top0boxes, though.
If you give more information about the problem you're trying to solve, you might get a more specific answer.
Thanks for the information. I was thinking of upgrading my router (Actiontec MI424WR rev.1) and internet service - I only have 75) I was thinking of getting my own router that just had ethernet ports but I see for FIOS I need to have a router with a coax input port for TV service. Are there better routers with a coax port out there than the Verizon routers ?
No but there are MOCA adapters which can be used with your own router.
there are no newer routers I am aware of with coaxial connections.
with a splitter you can use your own router and save rental fees each month. Then with the MOCA adapters and splitters you can have internet and tv. It takes some trial and error but it can be done.
a how to is here.
Read through what others have done. Good luck