Well I hung on in there like a dog with a slipper! :-)
My workstation in the den is lan attached and the Hurricane commands worked OK and I could get a score
of 20/20 from
http://ipv6-test.com/ and an animated turtle from the kame project.
This is with the modem IPV6 disabled and interestingly Firefox magically decided to prefer IPV6 over IPV4. Using the modem IPV6 route it would not attempt to connect with IPV6 unless I disabled IPV4. The fallback never worked.
Then used the forum topic
https://forums.he.net/index.php?topic=3067.0 to get my laptop working on IPV6. This worked OK but
http://ipv6-test.com/ only gave a score of 19/20 since the IPV6 hostname could not be resolved.
Just in case anyone else has a similar issue with the hurricane commands I will add this:
Before I found garrickstrom's topic I had tried using the hurricane commands on the laptop but they failed with "Element not found" on the last two lines, however after running the first two lines I ran the show interface command and replaced IP6Tunnel with the appropriate Idx form the show interface command.
netsh interface ipv6>sh int
Idx Met MTU State Name
--- ---------- ---------- ------------ ---------------------------
25 20 1300 connected WiFi
1 50 4294967295 connected Loopback Pseudo-Interface 1
15 20 1280 connected IP6Tunnel
so used
netsh interface ipv6 add address interface=15 address=2001:xxx:xxxx:xxx::2
instead of
netsh interface ipv6 add address interface=IP6Tunnel address=2001:xxx:xxxx:xxx::2