netgear xr500 ipv6 problems

I cant seem to get my netgear nighthawk xr500 to work correctly with ipv6, when i test my ipv6 it says i am getting it and everything is ok and i score 10/10 on the test, But i have 4 xboxes in the house and with ipv6 enabled, when there is a software update for the console it fails everytime. so to download anything like games or to update the firmware on any of the consoles i have to disable ipv6. 

my network service provider is callflow, also known as trooli, and i get uo to 1000 meg which is gurenteed 900 meg, my setup is ISP modem and ISP billion router which i then have a ethernet cable going from that into the yellow internet port on the back of the router. i then go into settings on the xr500 and i manually change the ip address to use a static ip address and then i log in to the billion router and put that ip address in to the DMZ, then i log back into the xr500 and i try to put the ipv6 on auto detect, passthrough and DHCP, i beleive i have tried them all. also on the QOS i tell the router i am only getting 600meg and i put the anti bufferbloat on 75% which means the router is only using 450 meg. so there should be no problem with packet loss, and when i do a test for bufferbloat i score A+. I hope someone can help and looks at this and says i am being really stupid and i just need to click on a few things. many thanks