Ubisoft broke this, but the modding community glued it back together. Follow the IPv6 trick and use Direct IP. You'll be executing coordinated grabs in no time.

If you are reading this, you’ve probably just spent forty minutes trying to get Splinter Cell: Conviction to work over LAN. You’ve seen the "Connection Failed" error. You’ve tried disabling your firewall. You’ve yelled at your friend over Discord.

But don't hang up your goggles just yet. After digging through ancient forum posts from 2010 and testing every possible registry edit, I’ve found the working recipe to get Sam Fisher sneaking with a buddy on a local network. Splinter Cell: Conviction uses a "virtual" LAN system that actually tries to ping Ubisoft’s matchmaking servers first . If it doesn't see a specific handshake, it locks you out. Even on the same switch, the game often refuses to see the lobby. The Fix: Direct IP + The "Switch" Trick Most guides tell you to use Hamachi or Radmin. Do not do that for a true LAN. Those add latency. You want a direct ethernet connection between two PCs (or a good router).