IPv6 might cause issues with the Internet connection being slow. Unless you absolutely need it, it is recommended to disable it.
sudo vi /etc/sysctl.conf
Add at the bottom of the file or change the lines:
#disable ipv6 net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1
Reload the configuration.
sudo sysctl -p
Disable IPv6 on bind9
If installed, you need to fix the IPv6 on bind9. This will not stop bind from blindly trying to use IPv6. You also need to alter
/etc/default/bind9, if of course you are using bind9:
sudo vi /etc/default/bind9
Add or modify the following lines:
# run resolvconf? RESOLVCONF=yes # startup options for the server OPTIONS="-4 -u bind" -