Welcome to the Make community!
That is because you have inserted a local IP address, which is not accessible from Make’s servers.
You need to use a public IP address, which you can purchase from your ISP, or rent a public web server.
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: Did you know, the concepts of about 70% of questions asked on this forum are already covered in the Make Academy. Investing some effort into it will save you lots of time and frustration using Make later!