There are a few reasons Screens might be unable to establish a connection to a remote computer over the Internet. To begin troubleshooting the issue, gather the following information: the remote computer’s local-network IP address, its MAC address, the Internet gateway/router’s public IP address, and the router’s public port number that Screens is connecting to. To collect this information:
- Use Terminal.app to find the remote computer’s local-network IP address and the MAC address.
- Open Terminal.app.
- Enter the following command:
- > ifconfig
- Locate the output for en0.
- The local-network IP address is listed just after inet and is made up of four numbers separated by dots/periods (.).
- The MAC address is listed just after ether and is made up of six pairs of characters separated by colons (:).
- Use Screens Connect to find the public IP address and public port number that Screens is trying to connect to.
- In the system menu bar, click the Screens Connect icon.
- On your keyboard, hold the Option key to reveal the public IP address and public port number.
- If Screens Connect isn’t installed on the computer, check your Internet gateway/router’s admin interface to find the public (sometimes listed as WAN or Internet) IP address and refer to your custom port forwarding rule to find the public port number.
- The app starts connecting, but the Connecting message doesn’t go away and the connection isn’t established. [See this support document.]