Lost IPv6 capability

[#1]

Last night, because of a strange large drop in connection speed some time in the last few days, I disconnected my Openreach FTTC modem for a couple of seconds. Got a decent sync, as expected - a bit down on what I get on a daytime one.
Both the strange drop and the one I triggered re-sync'ed so quickly my IP Profile and Current line speed were not affected.
Around 12:30 today I did the same and regained my full speed, which amusingly is so close to the original that the IP Profile is 0.01Mbps higher and the Current line speed of course unchanged.
However! That's the history. Now the problem.
The first thing I noticed was serious lag when loading pages. Typical in my experience of bng gateways. Checked my tbb BQM and sure enough the IPv6 one was solid red from my 12:30 re-sync onwards. So I checked my gateway and was on ptn-ag04! Not a bgn. Dropped the PPP session three times through my router, landing twice on bngs, and have now got to pcl-ag08.
That seems fine, but I have lost IPv6 connectivity completely. IPv6 BQM. My IPv4 one is fine. A tbb speed test picks up my IPv4 address, not the usual IPv6 one.
Any ideas or help please?
Edit - I typo'ed ptn-ag01 when I meant ptn-ag04.

[#2]

I thought the fixed IP didn't work on the bng's which would explain the monitor. Have you tried accessing an IPv6 site?

[#3]

It isn't working on either ptn-ag04 or pcl-ag08. Nor being seen by the tbb speed test which it has been seen by for ages. I don't know any IPv6-only sites, but I guarantee I won't be able to reach one :).

[#4]

http://loopsofzen.co.uk

[#5]

A thought: your router hasn't reverted to your normal login?

[#6]

Good thought, but no. It's picking up the IPv4 associated with the trial, not my original one. I did check that.
Edit - in fact demonstrated by the IPv4 BQM which is IP address specific.

[#7]

22:20 I swapped gateways again, landing on ptw-ag02. Much snappier, and with BQM latency lower than the very high pcl-ag08  by 2-3ms. Still no IPv6.

[#8]

you are using dhcp on ipv6?

[#9]

Have you tried:
http://test-ipv6.com
https://www.v6.facebook.com
They are both still working for me although my IPv6 TBB graph went to solid red at about 00:55 30 Jan 2015

[#10]

ipv6.com
You appear to have no IPv6 address.
It looks like you have only IPv4 Internet service at this time.
*******************************************************************
facebook.com
This page can’t be displayed
•Make sure that the web address https://www.v6.facebook.com is correct.

[#11]

OK, I now know my router settings are fine:-
IPv4 BQM. The red is when the router is either off (it was overnight) or the link to the modem disconnected. I believe that, strangely, I was on a bgn gateway for the following couple of hours but didn't bother checking my BQMs at the time.  (I was using my iPad). The tbb forums, access to the BQM page, BBC website pages all had horrendous lag, which for me is normal on bngs. The BQM tells only part of the story about the causes of lag - a few, to several, seconds for a bog standard BBC page.
I say "strangely" because look at my IPv6 BQM!
I disconnected again hoping to get away from bngs, having failed 10-12 times since I ended on one following my power cycle of the router to make sure that wasn't messed up, and at the end of the graphs you see me on ptw-ag02 and everything is flying.  Except the IPv6 BQM.
A response from one of the team would be appreciated. I see no point in contacting first-line support about IPv6 trial problems.
To users, are all other IPv6 BQMs running perfectly please?

[#12]

My IPv6 BQM is solid red.
IPv6 is working OK for me.
I am on pcl-ag06.
PeteB

[#13]

Is your BQM red because your TBB v6 address and PN currently signed addresses don't match?

[#14]

@Pete.
As before with IPv6.com and the v6,facebook link.
@Andy - the addresses have always varied. The first four entries fixed, the second four variable. Seen in what I get from tbb speed test results such as:
- ...1555:a15:40a3:11c0
- ...8b8:c133:7c7:68bb
- ...d32:62ac:472c:b99
I'm simply not being assigned an IPv6 address. Empty in the router.
In the router System log, (ignore the date as it simply hasn't picked up the time server as it doesn't have an internet connection at this stage), where you see the green patch at router bootup, we have:-
Jan  1 00:00:29 rdnssd[441]: Get IPv6 address from DHCPv6 & DNS from DHCPv6
Jan  1 00:00:30 WAN Connection: WAN was restored.
Jan  1 00:00:30 ntp: start NTP update
Jan  1 00:00:30 dnsmasq[377]: read /etc/hosts - 6 addresses
Jan  1 00:00:30 dnsmasq[377]: using nameserver 2001:470:20::2#53
Jan  1 00:00:30 dnsmasq[377]: using nameserver 212.159.6.9#53
Jan  1 00:00:30 dnsmasq[377]: using nameserver 212.159.6.10#53
But at 10:502 when I changed gateway to ptw-ag02:-
Feb  3 10:52:52 rdnssd[945]: Get IPv6 address from DHCPv6 & DNS from DHCPv6
Feb  3 10:52:53 radvd[993]: version 1.13 started
Feb  3 10:52:53 radvd[996]: Exiting, sigterm or sigint received.
Feb  3 10:52:53 radvd[996]: sending stop adverts
Feb  3 10:52:53 radvd[996]: removing /var/run/radvd.pid
Feb  3 10:52:54 radvd[1001]: version 1.13 started
Feb  3 10:52:54 radvd[1004]: sendmsg: Network is unreachable
Feb  3 10:52:54 rdnssd[945]: Get IPv6 address from RA & DNS from DHCPv6
Feb  3 10:52:54 rdnssd[945]: IPv6 router lifetime reach 0
Feb  3 10:52:54 radvd[1004]: Exiting, sigterm or sigint received.
Feb  3 10:52:54 radvd[1004]: sending stop adverts
Feb  3 10:52:54 radvd[1004]: sendmsg: Network is unreachable

[#15]

Currently on pcl-ag05.