Hamachi falls back to relayed when it cannot establish a direct UDP hole punch (due to strict NATs, firewalls, or network configuration).
A relayed tunnel occurs when UDP hole-punching fails. Your computer and your peer’s computer simply cannot find an open port to talk to each other. Common causes include:
This is the most reliable fix. You are telling your router: “Let UDP traffic on port 12975 through to my PC.”
How to do it:
Important: You must do this on both peers’ routers if both are behind strict NATs.
Here’s the battle plan. Try these in order—stop when you see green.
Hamachi relies on UDP Hole Punching. If both clients are behind Symmetric NATs (common in corporate networks, mobile hotspots, or strict home routers), hole punching fails. Hamachi gives up and routes through the relay.