This is potentially an hardware/antenna issue but just on the off-chance that someone knows anything about it being an issue on Ubuntu Linux, here's my question anyway.
Bluetooth reception on my XPS 13 (9350) seems extremely poor under Ubuntu Linux 19.10 (I don't know about Windows - haven't got it).
My bluetooth keyboard literally needs to be within 2 cm of the laptop or it won't work. Sometimes I even have to lift the keyboard to send the keystrokes I just made. Needless to say, it's impossible to work with this.
I've already tried copying the broadcom firmware from https://github.com/winterheart/broadcom-bt-firmware/blob/master/brcm/BCM4350C5-0a5c-6412.hcd (this corresponded to the ID from
/lib/firmware/brcm/ and rebooted but this didn't help.
The keyboard works fine with other computers (Windows).