Take the server out of the path.
In a peer-to-peer app, devices find each other and talk directly, encrypted end to end. When two of them can't reach each other, a relay passes the data along without being able to read it.
- Data goes straight from one device to another when it can, encrypted end to end.
- Any peer can drop out and the rest keep working.
- Peers share the load, instead of one server carrying it all.
