if you are behind a router or a firewall you have to open a part of your local network to the internet. on Portforward.com you can find easy descriptions with screenshots for a lot of routers/firewalls.
Andreas GSTools - Home of GSTScript 0.9.8: lua scripting for A6/7/8 GSTNet 0.7.9.20: network plugin for A6/7/8 GSTsqlite 1.3.7: sql database plugin for A6/7/8 3DGS Codebase: 57 snippets || 3DGS Downloads: 248 files