I've disabled ipv6 according to the description in: http://askubuntu.com/a/484487/229026, (As far I know, this article should also apply to Ubuntu 16.04) but netstat -nautp
is still displaying the following entry:
tcp6 0 0 :::22 :::* LISTEN 1289/sshd
Does this mean that ipv6 is still active?
The command: cat /proc/sys/net/ipv6/conf/all/disable_ipv6
displays 1
The command you used disables IPv6 on the network interfaces. That way your system won't be able to communicate with the outside world using IPv6.
The kernel module for IPv6 will still be loaded, and very probably needs to be to avoid breaking things. A lot of software depends on system support for IPv6 (as you have seen).
In general, disabling IPv6 is a bad idea these days as larger and larger parts of the internet depend on it. But if you really need to disable it then I think you already did the best you can do.