My team received an error while trying to connect to a WebSocket via VPN

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Hello, my team is developing a mobile application using Cordova and your plugin. I just received a report from my team this morning, she said she successfully tested a WebSocket connection in the application on her own development server. But, when she tried to test it on the company development server via VPN, she received an error that returns a connection error from a WebSocket, and she said it is quite hard to debug. Is there any way to detect the type of error and has anyone faced this issue via VPN before?