I have no idea why there was a suggestion of adding a second router; that would do nothing to help the original poster's situation unless the second router is connected to a second ISP that offers IPv6, or it has a tunnel, but if that were the case, what's the point of keeping the first router?! The fact of the matter is Fios sucks when it comes to IPv6 which is why here we are years after other ISP's have completely deployed it and they still offer nothing.
In any case, adding a second router will do nothing because if an IPv6-capable computer hears IPv6 router advertisements on its network interface, it's going to use SLAAC to give itself an IPv6 address (if one hasn't already been hard coded), and depending on the operating system and/or browser, will attempt to do DNS lookups for both A and AAAA records when you try to get to a particular destination, if an AAAA is available, it may try to use IPv6 to reach said destination.
Since the OP needs IPv6 on his LAN segment, there are a few options:
1) Set up an IPv4-only proxy server on the LAN and point the computer's browser at that for non-local web requests. Local requests, assuming there is a web server on the LAN, would still use v6, remote requests would hit the proxy server and since it is v4-only, would go out normally. This solution of course is http/https/ftp specific and would not help if you need to make other types of remote connections, like ssh, rdp, etc.
2) Do what I did; get Verizon to activate the ethernet port on your PON and plug your own router into it, getting their Actiontec garbage out of the way. Set the router up normally for IPv4 service; i.e. wan port uses dhcp from Fios, lan port(s) use whatever addressing scheme you desire. Directly connect to the Actiontec garbage router, set it to use the ethernet wan port as its wan port instead of the coax, and set the coax to lan. Plug the Actiontec ethernet wan port into your new lan segment. This step is necessary if you want your Fios set top boxes to continue to be able to watch video on demand and get programming schedules and software updates since they use ip over the coax. Now, the important step, get a free IPv6 allocation from Hurricane Electric's Tunnel Broker service at https://tunnelbroker.net/ Configure the router to do IPv6 tunneling using the steps they provide. It's fairly easy if you use DD-WRT and most any common home router hardware. Just please keep in mind that you need to set up firewall rules because you will be using publicly routable IPv6 on your LAN segment.
3) Add a second network card, create a separate network segment, whether physical or a VLAN if you have the appropriate switch hardware, put all the IPv6 devices on that segment and have no router. Now you can talk IPv6 locally on your eth1 interface, and eth0, or whatever your operating system of choice calls the first network card, will be used for non-local traffic and will be v4-only.
Thanks for that explanation.
It's pretty rediculous that verizon just doesn't support IPv6 yet. it's not like this was a surprise to them.
In any case, this is a moot point for me. I'm moving soon and won't be in an area where FiOS has service. Unfortunately for me, I'll be stuck using Comcast. 😞