{"record":{"id":"bdeb415545730869","repo":"nautechsystems/nautilus_trader","slug":"failed-to-connect-to-after-attempts-if","errorCode":null,"errorMessage":"Failed to connect to {} after {} attempts: {}. If this is a DNS error, check your network configuration and DNS settings.","messagePattern":"Failed to connect to (.+?) after (.+?) attempts: (.+?)\\. If this is a DNS error, check your network configuration and DNS settings\\.","errorType":"exception","errorClass":"anyhow::Error","httpStatus":null,"severity":"error","filePath":"crates/network/src/socket/client.rs","lineNumber":195,"sourceCode":"                        config.url,\n                    );\n                    error\n                }\n                Err(_) => {\n                    let error = format!(\n                        \"Connection timeout after {:.1}s (possible DNS resolution failure)\",\n                        connect_timeout.as_secs_f64()\n                    );\n                    log::warn!(\n                        \"Socket connection attempt {attempt}/{max_retries} to {} timed out\",\n                        config.url,\n                    );\n                    error\n                }\n            };\n\n            if attempt >= max_retries {\n                anyhow::bail!(\n                    \"Failed to connect to {} after {} attempts: {}. \\\n                    If this is a DNS error, check your network configuration and DNS settings.\",\n                    config.url,\n                    max_retries,\n                    last_error,\n                );\n            }\n\n            let delay = backoff.next_duration();\n            log::debug!(\n                \"Retrying in {delay:?} (attempt {}/{})\",\n                attempt + 1,\n                max_retries\n            );\n            dst::time::sleep(delay).await;\n        };\n\n        log::debug!(\"Connected\");","sourceCodeStart":177,"sourceCodeEnd":213,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/network/src/socket/client.rs#L177-L213","documentation":"SocketClient.connect_url retries the connection up to max_retries times; if every attempt fails, it bails with this aggregated error containing the URL, attempt count, and the last underlying error, plus a DNS-specific hint. It is the terminal failure of the connect loop, not a per-attempt error.","triggerScenarios":"Connecting to an unreachable/unresolvable socket URL so all retry attempts fail: wrong host/port, server down, firewall block, or DNS resolution failure — then attempt >= max_retries is reached.","commonSituations":"Typo in websocket endpoint hostname; exchange endpoint blocked by network policy/region; Docker/K8s DNS misconfiguration; server not started before client connects; stale endpoint after provider API version change.","solutions":["Read the embedded last_error to distinguish DNS failure vs connection refused vs TLS failure.","Verify the URL hostname/port and that the endpoint is reachable (ping/curl from the same host).","Check DNS configuration (resolv.conf, corporate resolver, container network).","Increase max_retries or add backoff if the endpoint is slow to come up; ensure the server is running before connecting."],"exampleFix":"// before\nlet client = SocketClient::connect(config, None).await?; // fails when server is down\n// after\nensure_server_up(\"wss://stream.example.com/ws\");\nlet client = match SocketClient::connect(config, None).await {\n    Ok(c) => c,\n    Err(e) => { log::error!(\"connect failed: {e}\"); return Err(e); }\n};","handlingStrategy":"retry","validationCode":"// Rust: pre-check DNS resolution before connecting\nlet host = url.host_str().ok_or_else(|| anyhow::anyhow!(\"no host in {url}\"))?;\ntokio::net::lookup_host((host, 443)).await.map_err(|e| anyhow::anyhow!(\"DNS failed for {host}: {e}\"))?;","typeGuard":null,"tryCatchPattern":"match SocketClient::connect(config, None).await {\n    Ok(c) => c,\n    Err(e) if e.to_string().contains(\"DNS\") => {\n        tokio::time::sleep(Duration::from_secs(5)).await;\n        SocketClient::connect(config, None).await\n    }\n    Err(e) => Err(e),\n}","preventionTips":["Verify endpoint URLs against provider docs.","Ensure the server is up before clients connect.","Check container/corporate DNS settings.","Use health checks + bounded retries with backoff."],"tags":["rust","network","websocket","connection","dns","retry"],"backgroundTag":"connection-refused","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}