michal

Would be great if you could edit your posts above (just mentioning 'Problems resolved, see few posts below' somewhere or as first line each). Regarding SSH problem: It's still useless without logs and/or debug output. Please see my signature regarding 'armbianmonitor -u' and keep in mind that when you try to establish SSH connection you can use as many '-v' switches to increase verbosity with ssh command (no idea about Windows though)

I had once an nmtui failure but that wasn't with Armbian but with Raspbian Lite instead: 
So without providing logs it's pretty useless to continue. Just to state the obvious: After fiddling around with config files that might interfere with network-manager  behaviour at least this service has to be restarted with systemctl (though in my Raspbian example above that didn't work and I had to issue a 'reboot' to get nmcli doing the job).
 
BTW: I recommend network-manager for a reason: since it avoids some common pitfalls with the traditional network setup in Debian/Ubuntu when there's more than interface (which needs some networking skills to be able to resolve, at least some basic understanding how the OS sets routes up and stuff like this -- with NM and untouched config files it should 'just work', if not then logs are needed since a simple 'nm... is buggy' is obviously both wrong and not sufficient to find any real bugs)

Hi, you were right, I needed to reboot the Orange Pi Zero after commenting out the interfaces file to start the nmtui and nmcli. Now, I am able to get the network lists and activate the proper Wifi connection. All mentioned problems, that I reported as bugs are gone. Thanks a lot for priceless advice - I have spent nearly 9 days playing with Wifi settings, before I wrote these lines into forum. The last thing: OPIz is connected via wifi to router, but SSH gives me Network error: Connection timed out. Ethernet works fine, though. Thanks in advance.

Effectively, there is no PA5 in the mapping.h, simply because PA5 is on Serial Debug UART0_RX.

Yes, you have to tweak mapping.h and rebuild the library. If you still having issue, do an "rm -rf build" and then redo an "python setup.py install"