G'day,
I'm an experienced and talented Linux DevOps engineer. Fixing annoying connection problems is something I do all the time.
There's a whole bunch of problems that could be causing this issue, could be a firewall, a routing issue, the wrong port number, an issue with your ISP, etc, etc. This means that it's very difficult to provide a precise estimate of time, it could be 15 minutes, or it could be five hours. (NB: I charge a minimum of one hour)