Arduino problem

I have two systems . The older system is 3kw with 6 microinverters reporting through an APS ECU-3 gateway and an arduino circuit board to upload data to pv outlook. Since installing a deco mesh lan with a new name and password , the gateway continues to send data to the EMA website , but no data is uploaded to pvoutput.
The other system is enphase reporting through an envoy gateway. After installing the mesh lan, this system initially also did not upload to pv outlook, but I fixed the problem by changing the wifi details in the envoy gateway.
What needs to be changed in the older system ? The aps gateway or the arduino circuit board ?I hope another member with an arduino board may be able to advise. My technical expertise is limited.

I assume that the existing Arduino was connecting to your home network via WiFi and not via Ethernet. If that is the case then the WiFi details also need to be updated in the Arduino. That is the SSID and passphrase of your new WiFi network.

Depending on the type of Arduino and how it has been programmed the WiFi details were either [I] hard coded into the Arduino [ii] saved / stored on a microSD card or similar physically attached to the Arduino or [iii] Manually entered into the Arduino by the installer with it running in some sort of WiFi hot spot mode.

If an SD card was used you should be able to alter the configuration by editing the config file using a computer.

If the WiFi credentials have been hard-coded into the Arduino you would need access to the original code.

In the third case you will need to either put the Arduino into hot spot mode or at least check to see if it is accessible wirelessly and then proceed from that point.

Thanks for the info . I can see a micro sd card in the arduino board and will have a shot at altering the config file.