Please provide more information on your setup to help us understand the problem.
If you want to connect an external device (like the robot) to your plug-in, you can run a web server inside the plug-in, such as nanohttpd or build your own server with Java.
If your question is how to connect the camera to a Wi-Fi network while it is in plug-in mode, then you just set the camera to connect to wi-fi router as a client. In this case, both the robot and the camera are connected to the same router.
If you are trying to connect your camera to the robot with Ethernet, then you need a y-splitter on the USB OTG adapter to power the camera when it is connected to the robot with Ethernet.