Adding an AC EV charger with separate IP address to Sigenergy ESS integration

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I've used Sigenergy Ess and correctly identified the following Sigen Plant , Sigen Inverter, Sigen Inverter PV1, Sigen Inverter PV2 and Sigen Plant, as per below. I also have a Sigen AC EV charger. The Inverter and Ac charger have different IP address and both are wirelessly connected to the same network. I've tried adding the Ac EV charger, with the add device button, then Ac Charger, Connected to Sigen Plant, entered the IP address of the AC charger, port 501 and device 1. Error is modbus connection failed to ipaddress:port. I've also tried other ports, to no avail. Note my inverter is also on device 1. I see documentation that the AC charger must be device 1? however its not clear if that is only when EV ac charger is directly connected to inverter. If inverter does need to be changed to device id2, who / how is this achieved?