Actiontec has partially remedied WCB6200Q's MoCA 2.5 incompatibility with a NCS firmware update 1.1L.10.20re. This firmware renders the WCB6200Q to be able to work with ECB6250 directly. ECB6250 uses the same MoCA chip as goCoax's WF-803M, so, if WCB6200Q works with ECB6250, logically, it should now work with WF-803M too without special configuration.
Fios-G1100 is a different story. It is made by Greenwave Systems and they have not provided the firmware remedy for the MoCA 2.5 incompatibility. In order to let G1100 join the MoCA network, you need to adjust WF-803M to D-band low. Also, Fios-G1100 is MoCA unbonded 2.0 capped at 500Mbps. If you are using it as your MoCA uplink to the gateway device, it would bottleneck the 1Gbps MoCA throughput of both WCB6200Q and WF-803M. You can eliminate the bottleneck by replacing it with another MoCA bonded 2.0 or 2.5 adapter.
For further inquires about Fios products and services, please come to forums.verizon.com . One of the CLs will be glad to help you.
Our product only can work with WCB6200Q with a D-band low mode, because WCB6200Q used a very old MoCA chip.
If you want to let them work together. Please note.
You can refer to the third diagram in this link.