Can't download software, port 18768 shows failure

Hi all

I’m not much of a techie but I’m trying. I keep having trouble downloading software and I thought it was my internet connection but I’m learning it’s somewhere in my security settings. Downloads just freeze up, time out, stop. I was just trying different browers and Opera asked me to test, it said port 18768 and then said failure. I open Active Connections and it shows listening on that port. How do I let downloads through without leaving my machine unprotected?