Hi, sorry for the late reply, just found your post.
RemoteGPIO supports only Dingtian Modbus protocol. Not sure the Waveshare is compatible. At some point we could add the support of additional Relay and Digital Input boxes.
You can leave the IP address empty. This is used to reset the Dingtian box in case it got stuck (this could happen if you miss-configure the RTU/USB interface) and is possible if the Ethernet interface is also connected.
I have tried to migrate the essential information into the new forum here: