I think this is the upstream bug: https://bugzilla.kernel.org/show_bug.cgi?id=197147, matches exactly my symptoms, Issue is present from kernel 4.13 upward.
** Bug watch added: Linux Kernel Bug Tracker #197147 https://bugzilla.kernel.org/show_bug.cgi?id=197147 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1721271 Title: Bluetooth and Wifi: coexistence Problem To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1721271/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs