If you're stuck on "Connecting..." or get a timeout right away, the issue is almost always on the network side. Check whether your router is dropping UDP packets — Rust uses UDP for game traffic, and some ISPs throttle it during peak hours. Try switching from Wi-Fi to a wired connection and restarting the router. If the problem persists on a specific server, that server may simply be overloaded or temporarily down.
Spike lag and rubber-banding usually come down to packet loss rather than raw ping. Run a traceroute to the game server IP to find where packets are being dropped. Common culprits: a congested hop between your ISP and the game server, or a router with SQM/QoS misconfigured. Setting your router's MTU to 1400 can help stabilize UDP traffic.
This usually means the Steam session token expired or the Steam overlay interfered. Fully restart Steam, not just the game. If the error says "VAC authentication" failed, run Steam as administrator and check that no third-party software is hooking into the game process.
If the world loads as grey or textures pop in slowly, the shader cache is likely corrupt. Clear it by deleting the contents of %APPDATA%\..\Local\Temp\Rust. Also make sure the game is installed on an SSD — spinning drives often can't stream assets fast enough during the initial world load.
Rust uses push-to-talk on V by default. If teammates can't hear you, first check that the correct input device is selected in Steam's Voice settings, not in the game itself — the game inherits the device from Steam. Also verify that no other app has exclusive control over the microphone.