What it means
Peers exchange encrypted traffic according to configured keys and routes. A successful handshake confirms a tunnel relationship, not that every application uses the intended path.
For hosting
Use one key per device, protect private keys and test forwarding, DNS and firewall rules. Revoke lost peers promptly.
Can one lost device be revoked independently?
Use a distinct peer key for each device and retain an understandable peer inventory. Shared keys make targeted revocation and incident review harder.