Android 9: Configure DNS while connected via cable
I've got an Android TV Box (orbsmart S86) running on Android 9. It is connected to the LAN and internet via a cable. Wifi is not used.
Now I've configured PIHole on another device and want to tell the android box to use the Pihole as DNS.
When using WiFi, I can go to the WiFi-settings and configure the settings there. How do I do this on this device?
So far I've tried
ndc resolver setifdns eth0 mydnsbut without luck.
Note, that I've got root access. Thanks in advance.
su setprop net.dns1
eg, setprop net.dns2 188.8.131.52