I'd suggest prioritizing testing of the v4.15.17 mainline kernel as this is the latest update bionic has incorporated. If that is broken then try v4.15.18 to see if there's a fix there, otherwise it points to some Ubuntu-specific changes or backports.
I'd suggest prioritizing testing of the v4.15.17 mainline kernel as this is the latest update bionic has incorporated. If that is broken then try v4.15.18 to see if there's a fix there, otherwise it points to some Ubuntu-specific changes or backports.