No! No! No!
Far too convoluted

. I have basically not set anything in my router config that matters except a static IPv6 address that has always been ignored by the system since. It never appeared anywhere after its first use where I copied it from tbb's "What is my IP". Within hours my visible IP address changed and the BQM stopped working. That was the problem I have solved much more simply than yourself.
So lets start again, using a single capital letter per hex block.
I have A:B:C::/48 and A:B:C:D::/64
Note that I have never ever seen D appear anywhere.
| Text |
1
23
45
67
8 | IPv6 Address. . . . . . . . . . . : A:B:C:0:F:G:H:I(Preferred)
Temporary IPv6 Address. . . . . . : A:B:C:0:J:K:L:M(Preferred)Link-local IPv6 Address . . . . . : Z::F:G:H:I%3(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.2(Preferred)Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 03 December 2016 14:42:12Lease Expires . . . . . . . . . . : 03 December 2016 18:26:06
Default Gateway . . . . . . . . . : Z::N:O:P:Q%3 |
The Temporary IPv6 Address is the one visited websites see. It changes frequently, as in several times a day. I assume that is some sort of security defence against DDOs attacks and the like, as within hours of a site acquiring it, it ceases to exist/go anywhere.
What I also noticed was that the IPv6 address in the first line, and the Default Gateway at the bottom, never change. The default gateway is the one used to access by telnet or browser. Whereupon building on you idea of pinging a device but not wanting it to be something attached to the router, I used the A:B:C:0:F:G:H address to overwrite whatever the tbb BQM defaulted to, which was of course my Temp address at the time.
Job done. No setting up my own /64 address range and fixed-allocating any addresses. I just took what was presented, once I understood it, and used it.
Then, hours after I got it working, and after a switch off and on of the router which worked, I put the pingable address into the fixed IP address field replacing the one that gets ignored, purely so as not to confuse things in the future. I assume it is still ignored.
What I may try for fun in a couple of days is remove that and set the IPv6 address acquisition back to Automatic. I get the feeling the top line is preset by AA in a similar way to the static IPv4 address. I shall also probably find out when I put the ZyXel into bridge mode and feed my ASUS WAN port from it.
I have an unrelated problem to ask AA about first. I want the line stable for now instead of me messing about any more

.
As an incidental point, when examining the Info on the Network Map page of the ZyXel, I see it gets the SLAAC IPv6 address of attached kit wrong.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
My broadband basic info/help site -
www.robertos.me.uk. Domains, site and mail hosting -
Tsohost.
Connection - AAISP Home::1 80/20. Sync 60000/15336kbps @ 600m. -
IPv4 BQM IPv6 BQM