WAN to LAN to connect openWRT router to block telemetry data from smart devices

hi there,

I have the the following zyxtel from my provider Odido, in the netherlands:

Model Name VMG8825-T50
Firmware Version V5.50(ABPY.1)b24_20240613

i have a WAN port which i would like to convert to a LAN port. is there any way i can do this? I receive internet over dsl, so my wan port is unused.

I have gone trough ALL the configuration pages in advanced mode, but nothing.

I consider myself to be a 'advanced' computer user since i'm very familiar with Linux. I'm however not that experienced in the networking world yet. I was hoping find a 'convert wan to lan'-switch.

I want to use the was port to connect a openWRT router so connect all my home appliances to to block their telemetry data. I want to limit the amount of data going trough american big tech servers as much as possible, therefore I'd like to use openWRT.

Thank you in advance.

Johan