[6.7.2+] IPv6 internet access despite "IPv4 only"

This bug report is based on the following thread:

While the version of Unraid I am using there is 6.8.0-rc7, I have also tested with 6.7.2 as well as both in safe mode, the results always being the same. My Unraid server appears to have IPv6 internet access despite it being disabled from within the settings.

Summary:

When choosing "IPv4 only" in "Network Settings",

IPv6 network addresses are assigned to network interfaces

Those network interfaces can access the local network via IPv6

They can be pinged via IPv6

Those interfaces can access the internet via IPv6

I believe the intended behaviour when choosing "IPv4 only" in Network Settings is that IPv6 is disabled

IPv6 network functionality is only disabled after the follwing commands:

sysctl net.ipv6.conf.all.disable_ipv6=1
sysctl net.ipv6.conf.default.disable_ipv6=1
sysctl -p

Fresh diagnostics attached,

Thanks.

tower-diagnostics-20191202-0736.zip