You may be having connection issues because of IPv6 even though it shows an IPv4 connection.
How do I prove ipv6 has been successfully disabled
There seems to be much disagreement between distros regarding how ipv6 is disabled, even between different versions of the same distro. Rather than just follow instructions for disabling ipv6 for a given distro, I would like to also test that ipv6 is not used any more. Any software or executable that relies on ipv6, that I can use to confirm that ipv6 has been successfully disabled?
They should all be 1.
Disabling IPV6 is best done via sysctl. In ubuntu, add the following to /etc/sysctl.conf
# Disable IPV6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
net.ipv6.conf.lo.disable_ipv6 = 1
ifconfig should not mention an IPV6 address on any interface after you have rebooted.
IPV6 should still be considered in your security setup on your machine, just in case it is, for example, re-enabled after an upgrade etc.
To check if IPv6 is enabled, just simply use netstat:
If you see any "tcp6" entries, then IPv6 is not disabled.
You may be also having IPv6 problems in your browser.
For Firefox, type about
:config in the browser bar.
Filter with network.dns
Change IPv6disabled to true