IPv6 addresses not resloving properly when using Technicolor router

[#1]

I recently swapped my HH3 for the PN Technicolor router to try and sort a line dropping issue.

Problem went away and speeds eventually increased BUT having massive issues with IPv6 sites.

I use Linux and the problem is most apparent with repositories which use IP6 - connections cannot be established or come and go at random. This is the equivalent of WIndows Update not working so it's fairly critical.

Put the BT HH3 back on and all problems vanish - except connection drops again.....................

[#2]

Do you have IPv6 Internet connectivity? If not, perhaps the solution is to configure things not to ask for IPv6 addresses. Otherwise things may be wasting their time trying and failing to connect to IPv6 addresses.

[#3]

I have already disabled ip6 via sysctl.conf - also told network interface to ignore ip6

Check via ifconfig - no ip6 address showing.

So, as far as I can see on my side ip6 is disabled.

Run apt-get update - stalls at various points though pinging the url does give correct ip4 address.

Swap router back to BT HH3 - on which ip6 is disabled - do nothing else at all, run apt-get update  and all works smoothly as it should.

Router faulty?