If someone has the same issue and needs help:
I had continous wifi problems. In a nutshell, arbitrary disconnects, regardless if headless or headed mode. Tried everything for weeks – issue persisted.
The solution was so simple: enforce 2.4 GHz vs 5 GHz if your wifi access points has both.
Thus, e.g.:
nmcli connection modify “WIFI-NAME” 802-11-wireless.band bg # 2.4 GHz