@ajkan001: Actually, I think I did. Apparently, 18.04 needs dnsmasq to be running, whereas 16.04 didn't seem to require the user to even have dnsmasq installed. So, make sure you have dnsmasq installed, using (without quotes) "sudo apt install dnsmasq-base". Sometimes, however, dnsmasq just doesn't want to play nice. In that case, use (again, without quotes) "sudo pkill -x dnsmasq" or "sudo killall dnsmasq" (either one will work), and try again.
PS: I probably should have mentioned something on this bug report before, but I guess I forgot. My apologies. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to network-manager in Ubuntu. https://bugs.launchpad.net/bugs/1788081 Title: Cannot connect to "shared" ipv4 network ("Error: Connection activation failed: IP configuration could not be reserved (no available address, timeout, etc.)" Status in network-manager package in Ubuntu: Confirmed Bug description: I have a connection profile which is supposed to allow my computers to talk to eachother over an ad-hoc ethernet connection. For me, this is mostly useful for when I need to transfer large files over from one computer to another (the only network I have is WiFi, and it's painfully slow). So, If I need to transfer files from machine A to machine B, I just use an ethernet cable. Easy-peasy. However, after upgrading one of my machines from Ubuntu 16.04 to 18.04, I find that said machine can no longer create such a network. If I try to active the profile graphically using nm-applet, it fails without displaying any error messages. However, If I try to activate it from the command line with "nmcli con up id Wired\ Connection\ 2", it fails with the following message: Error: Connection activation failed: IP configuration could not be reserved (no available address, timeout, etc.) While typing this bug report, I ran the "ubuntu-bug network-manager" command, and will post the results below. If there's anything else I can do (I can't read/write code very well, but I can test code, and get any additional information, so long as I'm given clear instructions on how to do so), please let me know. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/network-manager/+bug/1788081/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp