This is still an issue in Ubuntu 16.04 up to the current date. It is an interface bug, as Robin Sheat pointed out.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/269910 Title: Netmask automatically changes to 24 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/269910/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs