Problem is caused by Dell BIOS 1.11.2, rolling back to 1.10 solved it.
Hopefully the next BIOS version will be fine.
EDIT: BIOS 1.12.0 has been fine, but the latest 1.13.1 (published January 6th 2020) has recreated the problem. Again, rolling back to 1.12.0 is the solution, but I would like to understand how the official BIOS can do this.
I also tried ...
Elementary is based on Ubuntu 18.04 and use an old Kernel (5.4). The only way for me to use my Bluetooth devices was upgrade to newest kernel (5.13.4)
Add the repository:
echo 'deb http://deb.xanmod.org releases main' | sudo tee /etc/apt/sources.list.d/xanmod-kernel.list
wget -qO - https://dl.xanmod.org/gpg.key | sudo apt-key --keyring /etc/apt/...
Please run Commands in this order, It should definitely work:
enter, then your password
su - -s /bin/bash lightdm
dbus-launch gsettings set org.gnome.settings-daemon.plugins.power
There is a workaround, but it requires a wired connection and Secure Boot enabled to get started.
There is a bug in the intel_lpss driver which causes booting to fail with Secure Boot disabled. This applies to both the installation media and the finished installation. In BIOS settings, you need Secure Boot enabled for the installation. We'll disable it ...