The wifi worked before the initial setup, but after reboot it stopped working.
raspi-config says no wireless interface found when trying to set up the wifi.
Checked the file /etc/network/interfaces and it states:
source-directory /etc/network/interfaces.d (this directory is empty when checking)
script /root/bin/map_iface (this directory is empty when checking)
source /boot/realtimepi-network.txt (this file does not exist)
It seems the wifi (wlan0) is not properly initialized at boot.
How can I solve this?