I recently purchased a VPN account, so I can get first-hand experience on using such technology, and decided to give NordVPN a try, as their service seemed to be affordable for my educational budget. After downloading and installing their client, I noticed that I could still not be “protected” so I decided to contact their Customer Service via chat.
A nice representative told me that their service currently does not support IPv6 (for whatever reasons that I didn’t ask) and that I should disable IPv6 on my active network interface, for the VPN connection (to their network) to work properly.
The first guide that I consulted after a quick web-search pointed to an “Off” option in the TCP/IP tab of the network interfaces, which seems unavailable for my Yosemite 10.10.5 installation. I was puzzled as I had seen screenshots of that option being there, on other websites.
Apparently, this missing “Off” option is the case for fresh El Capitan 10.11 installations, too.
Upon further search, I stumbled across an older article on OS X Daily that shows how to directly switch IPv6 feature off, via a special Terminal command.
I studied the command and realized that the article had reference to the generic interface(s) of Mac OS X, but on my machine these weren’t valid. This action thus requires some more attention if you wish to disable IPv6 via Terminal, namely to type the exact name of the interface to be disabled. In my case, I had a different name — and this exact name, as it appears in the list of “Network” settings, should be copied across.
Rather using the generic interface names, such as:
networksetup -setv6off Ethernet
networksetup -setv6off Wi-Fi
…I had to use my own, custom-named interface instead (with quotes):
networksetup -setv6off "Ethernet (en1)"
This command prompts the user to enter his/her administrator password, and immediately applies the setting that results to an “Off” being now available as an option.
Reverting to “normal” is equally easy; either select “Automatically” in the TCP/IP tab of the network interface in question (and apply) or use the corresponding command in Terminal:
networksetup -setv6automatic Wi-Fi
networksetup -setv6automatic Ethernet
Now we can use the VPN services… Hopefully, a future update (to the NordVPN client, that is) will render such action obsolete.