Running backend must have access to PLC over OPC-UA. If no connection to PLC established, try it with Prosys OPC UA Browser or UaExpert.
Mobile device must have access to running backend:
Both devices part of same local network
Connect from mobile device to hot spot at notebook or vice versa
Check firewall of running backend system. Configured port (default: 8080) must be open for incoming connections.
Connect to backend
Enter URL with port at mobile browser to access service ui backend. Consider that IP address of WI-FI connection should be used while accessing over a hotspot. Use standard ethernet IP address if backend is located at same local network. Use device name instead of IP if a correct DNS resolution is supported at internal network.