Actually, installing and running the upstream kernel was much more painless than anticipated
Same problem with 4.0.0-040000rc5-generic ** Tags added: kernel-bug-exists-upstream -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1436891 Title: Cannot connect to any WiFi access point which runs wireless-N Status in linux package in Ubuntu: Confirmed Bug description: When attempting to connect to a WiFi access point with N wireless, two popup messages appear: Connection 'SSID' deactivated. The WiFi network could not be found Expected behaviour: Connects to network. Minimal demonstration: connect to a WiFi access point by both LAN and WiFi B/G. Log in to access point, change it to B/G/N. Connection is lost, cannot be re-established until reverted to B/G. Previous troubleshooting located here: https://www.kubuntuforums.net/showthread.php?67556-Can-t-use-wifi Description: Ubuntu Vivid Vervet (development branch) Release: 15.04 linux-firmware 1.143 Can connect normally (with N) from 14.04.2 and 14.10 live CDs. Can connect in 15.04 if and only if N deactivated in access point. ProblemType: Bug DistroRelease: Ubuntu 15.04 Package: linux-firmware 1.143 ProcVersionSignature: Ubuntu 3.19.0-10.10-generic 3.19.2 Uname: Linux 3.19.0-10-generic x86_64 ApportVersion: 2.16.2-0ubuntu4 Architecture: amd64 CurrentDesktop: KDE Date: Fri Mar 27 00:14:58 2015 Dependencies: InstallationDate: Installed on 2015-03-04 (22 days ago) InstallationMedia: Kubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150224.1) PackageArchitecture: all SourcePackage: linux-firmware UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1436891/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp