Dedicated Server Connection Issues

So one of my friends couldn’t connect to a server I made in gmod. So I decided to create a dedicated server because I thought it might fix the issue. I finished making the dedicated server and it works perfectly except for one thing. All of my other friends that I play GMod with can join the server… Except for one! Everytime he tries to join, he gets an error message saying Connection failed after 4 retries. Why is it just him but no one else? Any and all help is appreciated :quagmire: :smile:

He probably has firewall issues.