I've a Raspberry Pi 4 (b) with Ubuntu Mate 20.10 running very well.
I've rigth configured the wifi wireless connection to my wireless network and it works OK
If I have plugged it to any display, it boots very well, mate desktop is loaded OK and the wifi wireless connection to my wireless network works OK
But If I boot it without display connection, the wireless connection is NOT brought up, so it does not connects to my wireless network.
It seems that the wifi wireless connection 'belongs' to the user that brings up the Desktop Xserver or something like that...
Any help please?