Netplay Issues..

[Starshade]

Hey guys. So I got dolphin for the sole purpose of playing Melee on my computer and using Netplay to get better. I get everything set up like this guide (https://www.smashladder.com/guides/view/25jx/melee/melee-netplay-guide) says, but I cannot join any games. Oddly enough, I can host games, but they are incredibly laggy. When I try to join, I get about 4 seconds of waiting, then get a "Failed to Connect!" dialogue box. I am out of ideas for help. Using 4.0-7840 for this, like the site says to. Help please.