GNOME Bugzilla – Bug 751199
It is impossible to set custom IPv6 DNS servers
Last modified: 2015-11-08 20:20:03 UTC
Step 1: Open wifi settings for your active network. Step 2: Go to the IPv6 tab Step 3: Enter in custom DNS servers, such as "2001:4860:4860::8888" and "2001:4860:4860::8844" Step 4: Apply Step 5: Reopen network settings Expected: The ipv6 dns servers I added are present Actual: The ipv6 dns servers are "corrupted" meaning that I can't edit anything for this network until I clear out the bad servers. Here is a video demonstrating this behavior: https://colemickens-screenshots.s3.amazonaws.com/screencast-2015-06-19-003354.webm
You are using the NetworkManager integration in gnome-control-center. Reassigning bug.
*** This bug has been marked as a duplicate of bug 746932 ***