How to find out what is causing problems with ipv6 in windows 7?

Question

Windows

There is a local network with 3 windows 7 computers, 3 android phones and 2 ubuntu (14 and 18)
In the local network, using 6in4, ipv6 is configured from Hurricane Electric
Ubuntu, android and the router itself do not experience any problems with ipv6 even after a long connection time
All three windows systems are installed from one image.
The system last reinstalled in 2016 has no problems with ipv6
The system installed in 2017 works fine with ipv6 for about 30 minutes (at 29 there is still a connection with ipv6. at 31 only the local address remains (even the ipv6 gateway is not displayed))
The system that was installed in 2015 worked fine with ipv6. After reinstalling in 2018, the problem is the same as in 2017. As a result, we can conclude that the problem is not in the 2017 hardware, but in the system
. If you run the Live version of ubuntu on any of the windows machines, there are no network problems.
What I tried:
1) Reconnecting to the network ( like enabling/disabling in device manager) does not work. Only reboot helps
2) Installing the same version of the network driver as in 2016 does not help
3) There are no events in the windows log (3 minutes in both directions) with the ipv6 shutdown time (after 30 minutes after the system starts)
I attach the output of ipconfig / all up to 30 minutes and after on one of the problem machines
Before

After

Answer 1

As it turned out, dweb (or rather, its brandmauer) was to blame for this circus (AVG is installed
on the third windows) Something like this
happened:
1) windows received an ipv6 address before loading the firewall
2) after 30 minutes, windows updated the ipv6 address but did not receive a response
I would very much like to find out what is so terrible that dweb sees in ipv6?
The process of finding out the causes of this problem took such a long time since I had never experienced problems with dweb products before.