Part of the GUI freeses if network connection is initialized via network manager

[Jürgen Knauth]

I'm using a Dell Notebook to run Ubuntu Mate on. The system has been working quite well for about two years. Then the system crashed and I had to do a complete reinstallation but that's not the point. The point is: The new installation now causes me troubles.

I'm now running an up-to-date Ubuntu Mate 17.10. When I log in and click on the network manager to connect to a WLAN I see the icon animation for a few seconds and then the nm-applet freezes. I can move the mouse, even move other windows around, input something there, even open the menu, but the mw-applet will not respond to any kind of input for about 50 to 55 seconds. After that time everything returns to normal. In the last installation of Ubuntu Mate never had this problem.

If I disconnect a network connection using the mouse menu at nm-applet it is worse. Then the whole GUI freezes for that time. Then no GUI updates are performed at all. I have to sit there and wait for almost a minute and then I can continue working. I NEVER saw this behaviour on any Linux machine I ever worked with before.

It is even enough to active an interface on the command line, then click on the nm-applet to open a menu a second later, and then the whole GUI system will freeze. It seems to be correlated with a reaction on a state change but I can not be sure: I've no idea about how the nm-applet is built internally.

The question is: How can we improve on this freezing-bug? System log does not provide any hint at all what's going on. No warning, no error, just regular log output related to setting up the network connection.

System: Ubuntu Mate 17.10
Kernel: 4.13.0-32-generic
Device: Dell Latitude E5570
CPU: Intel Core i5-644HQ
LAN: enp0s31f6 Intel Ethernet Connection (2) I219-LM with driver e31000e
WLAN: wlp2s0 Intel Wireless 8260 with driver iwlwifi

[Martin Wimpress  (flexiondotorg)]

Please provide the exact steps required to reproduce this issue.

[Woo (woo3)]

Fist: Thank you for hearing from some one here.

Second: Here are the exact steps: Turn off WLAN. Reboot a computer exhibiting these problems. Log in. Click with right mouse button on the NM-Applet. There you are.

But I'm not sure if that helps you. As I said: The system has been working quite well for about two years. The new installation behaves like this. And it's the only system I know that behaves like this. And I cannot track down that problem as I don't see any error message. I've no idea where this comes from.

In the meanwhile I've more experience with that bug. It affects network functionality in general. If I read mail with Thunderbird, the application freezes for some time, but recovers after that. But I've a messenger named "Signal" that does not seem to recover: It works in general, but freezes all the time after a single message has been received. (Interestingly AFTER it has been received.)

I've no idea what's causing this. It is very unlikely that this is a hardware bug as the hardware works well and it worked well with other versions of Ubuntu-Mate. And it worked well on the installation media I used for the installation.

[Woo (woo3)]

Update: For unknown reasons the system now seems to use IPv6 with priority over IPv4 on wired connections (and on wired connections only). I've no idea why as I didn't change anything yet. Things work much better this way: No application hangs in this specific configuration. Very strange.

[Launchpad Janitor (janitor)]

[Expired for ubuntu-mate because there has been no activity for 60 days.]