Serial device server cross-network segment :

 

If the IP of the device is not in a network segment with the communicating PC, and it is directly connected to the network cable, or is under the same sub-router, then the two cannot communicate at all. For example, device’s IP: 192.168.1.66  sub network mask: 255.255.255.0 PC’s IP: 192.168.0.161  sub network mask: 255.255.255.0  Since the IP of the device is 1.66, it will not be able to log in to the device web page on the PC, nor can it ping it.

If you want to be able to communicate, you need to set the sub network mask of the device, PC and the router to 255.255.0.0, so that you can log in to the module web page.