My setup is 2H/4J all connected via Ethernet (wired cables) into a switch and then into an Airport Extreme. The Airport Extreme is running latest firmware (7.6.1) and I also have IPV6 enabled on the network. And everything is working fine. So it would seem there is something unique in your setup or environment...
In one of your earliest posts you said:
we have 2 complete set ups for surveillance systems connected to this router. Neither would work when initially connected via Ethernet cables to this router. We had to manually change the DHCP to static, the subnet mask to match the router and input the correct MAC address, primary and secondary DNS settings IN EACH DEVICE
If you perhaps meant "and input the correct IP address" (versus MAC address) you seem to be saying that your ISP requires that your home network not have any DHCP assigned addresses -- every device needs to be individually configured with a static IP address. If so, that would be a *very* unusual setup. And (as you've discovered) I don't believe there is a way to configure a static IP address within Hopper or Joey. I don't know the particular requirements of your ISP, but seems very strange that you wouldn't be able to set a static IP address on the external (WAN) side of the Airport Extreme (this static address would be assigned by your ISP) and then let the Airport Extreme do it's "normal" thing of assigning DHCP addresses to the devices on your local (LAN) side and do NAT translation of the local LAN traffic through the statically assigned WAN address.