ROCK64 no serial devices found !?

Hello,

I used an FAN HAT which is controlled via i2c and found as serial on an RPI3 (only for testing).
If I use ist on an ROCK64 (target solution), dietpi-config says “no serial device found”.

I user dietpi v6.26.3.

Could this be an kernel problem ? Maybe is this supported on ROCK64 ?

Regards