Public bug reported: If a process binds 127.0.1.1:53 and the network-manager ist started, it tries to use this port (dnsmasq). It waits until the port is available. That means no interaction with the network-manager is possible. So unity-control-center stucks if "Network" is clicked or the nm-applet does not respond if the user tries to change connection settings.
I think there should be a message that explains the problem: "network- manager tries to set up dnsmasq on 127.0.1.1:53, but this port is already in use. Retrying ..." and the associated GUI components should stay responsive, but only the blocked options should be shown as blocked by the problem. You can verify the bug with the provieded script. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: network-manager 1.2.6-0ubuntu0.16.04.1 ProcVersionSignature: Ubuntu 4.4.0-83.106-generic 4.4.70 Uname: Linux 4.4.0-83-generic x86_64 NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia ApportVersion: 2.20.1-0ubuntu2.6 Architecture: amd64 CurrentDesktop: Unity Date: Sun Jul 16 02:01:03 2017 IfupdownConfig: # interfaces(5) file used by ifup(8) and ifdown(8) auto lo iface lo inet loopback auto enp0s25 iface enp0s25 inet manual IpRoute: default via 10.149.15.253 dev wlp3s0 proto static metric 600 10.149.0.0/20 dev wlp3s0 proto kernel scope link src 10.149.5.84 metric 600 169.254.0.0/16 dev br-d5edc0a60a9c scope link metric 1000 172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown 172.18.0.0/16 dev br-d5edc0a60a9c proto kernel scope link src 172.18.0.1 NetworkManager.state: [main] NetworkingEnabled=true WirelessEnabled=true WWANEnabled=true SourcePackage: network-manager UpgradeStatus: No upgrade log present (probably fresh install) mtime.conffile..etc.NetworkManager.NetworkManager.conf: 2017-04-14T17:29:21.619202 nmcli-nm: RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN running 1.2.6 connected started full enabled enabled enabled enabled enabled ** Affects: network-manager (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug xenial ** Attachment added: "script triggers the problem" https://bugs.launchpad.net/bugs/1704600/+attachment/4915321/+files/crash_networkmanager.bash -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1704600 Title: network-manager stucks if 127.0.1.1:53 is in use To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1704600/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs