[HowTo] Get Wi-FI working on host and guest if you're using LXQT/connman/Virt Manager

[Enigma83]

OK, so, a few months ago I ran into an issue where Internet connectivity stopped working on host/guest OSes, while using the combo of LXQT, connman, and Virt Manager. My home Internet connection is 100% wireless, so I cant say if this applies to wired too. Because I exclusively use wireless Internet, creating a bridged network adapter in Virt Manager wouldnt be a solution.

I installed LXQT and standard system utilities using the net install ISO. By default, the LXQT package uses connman as network manager, and CMST as a GUI frontend for connman. Anyway, afterwards I installed Virt Manager and downloaded a Windows 10/Manjaro ISO. Then I set up VMs for both. Up until this point, all seemed to be working fine. But as soon as the guest OSes booted, I noticed a complete loss of network connectivity, both in the host and guest. I used simple ping command tests, and a Web browser, attempting to reach google.com. ping said that Google couldnt be reached, and webpages for common sites failed to load. However, as soon as i shut down the VM, the host suddenly had working internet again.

I'm not the type of guy that walks away from problems, I like to find answers. Several months later, still unresolved, I was determined to find a fix.

So I went to the connman page on the Arch Wiki, and the section tagged "3.7 Blacklist interfaces" caught my eye. This part, specifically:

If it does not already exist, create /etc/connman/main.conf:

[General]
NetworkInterfaceBlacklist=vmnet,vboxnet,virbr,ifb,docker,veth,eth,wlan

So I opened that file, and noticed that the NetworkInterfaceBlacklist line was commented out. While a VM was running, i ran the "ip link" command to get a list of interfaces. The interfaces titled "virbr0" and "vnet1" seemed relevant to Virt Manager. As root, I opened /etc/connman/main.conf, then changed the line so it looks like:

NetworkInterfaceBlacklist = vmnet,vboxnet,virbr,vnet,ifb,ve-,vb-

A reboot was enough to get full Internet connectivity in host/guest.

This probably also applies to other virtualization solutions like VMware, VirtualBox, or anything else that creates virtual network interfaces. You just need to get the interface name, remove the comment, edit the line, then either restart the connman service or reboot. I realize this "guide" may be of no use to someone not using the combo of LXQT/connman/Virt Manager/ wireless Internet. But I'm also certain that I'm not the only Debian user to experience this.

At first I thought this might be a connman bug, since this issue doesnt occur when connected to wireless internet via wpa_supplicant or Network Manager. But since blacklisting seems to be the fix, no need to report.

Edit: I've recently stopped using connman after having other issues with it. So I apt purged connman/cmst, I now am using wpa_supplicant/dhclient to connect to wifi.