Two questions to start with:
1. Does it work in its current configuration with you friend? If not, first get it working there and try again at home.
2. Does your friends PC work with you? If not, it's not your PC that is in error, but the thing (router, modem?) it is connected to and beyond.
Isn't 1 Gbps very fast for an internet connection? Where I live, even a glass fiber connection usually is limited to 100 Mbps for consumers, 200 Mbps for small and medium businesses.
1 Gbps equals a 2 hour movie in standard DVD quality (4.7 GB) downloaded in 10 seconds or so. You can't even write it to your hard disk that fast.
My internet is connected but not working properly. Downloads stop after a few kb, pages don't load, torrents are not working, etc.
The thing is that I called tech support for My ISP (RDS Romania) and they brought a laptop on which they connected the cable, and on their machine it was working fine.
I also took my PC to a friend's house (with exactly the same ISP and internet plan, cable, modem, everything) and his internet was working on my PC.
My internet plan is for 1000 mbps, and it wasn't working. I changed the network card options to limit it to 100 mbps and it worked for a few days until I tried some commands (reseting ipv4,ipv6 and winsock, changed MTU from 1500 to 1492) to make 1000 mbps work, then it stopped working at all, even at 100 mbps.
Windows 7 Ultimate Service Pack 1
NEW Network card: D-Link DGE-528 T Gibabit Ethernet Adapter