The gateway is the local server that routes your messages. When it fails, you'll see one of a few specific errors.
"Gateway start blocked: set gateway.mode=local" means local mode isn't enabled. Set gateway.mode to "local" in ~/.openclaw/openclaw.json.
"Refusing to bind gateway without auth" means you're trying to bind to a non-loopback address without authentication. Bind to 127.0.0.1 instead.
"Another gateway instance is already listening" means a port conflict. Run openclaw gateway install --force to reclaim it. If a simple openclaw gateway restart doesn't fix your issue, that force reinstall usually will.