fatal: unable to access 'https://github.com/achanghello/ac-ui.git/': Failed to connect to github.com port 443 after 21104 ms: Timed out

This error message indicates that the Git client is unable to connect to the GitHub server. The most likely cause of this error is a network issue, such as a firewall or proxy server blocking the connection. To resolve this issue, try the following:

1. Check your network connection to ensure that you are connected to the internet.
2. Disable any firewall or antivirus software that might be blocking the connection.
3. If you are behind a proxy server, configure Git to use the proxy by running the following command in your terminal:

git config --global https.proxy http://proxy.example.com:8080

Replace `proxy.example.com` with the hostname of your proxy server and `8080` with the port number.

4. Try cloning the repository again after waiting for some time, as there might be a temporary issue with the GitHub server.

If none of these solutions work, you can try contacting your network administrator or GitHub support for further assistance.