To prevent NM form destroying content of resolv.conf:
[main] ... dns=none ...
nmcli con reload
Do not touch any interfaces defined in /etc/network/interfaces
[main] plugins=ifupdown,keyfile [ifupdown] managed=false
Specify interfaces to ignore:
[main] plugins=keyfile [keyfile] unmanaged-devices=interface-name:wlan0mon unmanaged-devices=mac:xx:xx:xx:xx:xx:xx
nmcli con reload