Thank you for your replying. I just turn off the firewall, but it still occurs the same error message. Maybe I need to show you the network structure.
As you see, I find that the IP address of the OPC UA Server on site and routers in the office is on the same network segment. Is it possible that Ignition get the Host Override (192.168.1.5) and it actually only searches devices conneted Router A instead of OPC UA Server on site?