esp32 wifi connection with raspberry pi 4

[bjarnej]

In my case it is a RPi Zero W that does not recognize the SSID from the RPi4. From the Openplotter network app I have the 5 GHz checkbox unchecked - think that means it is running 2.4g? I've tried a number of channels without success. The RPi Zero W sees other networks (my own and some neighbors) and is able to connect to my home wifi. 

But from other devices like my windows10 or tablet the RPi4 Wifi is visible and connectable. For now I have approx 1 meter between the two RPi's due to my test setup - could this in any case be a problem?

Thanks