ERR_TIMEOUT embedded network_error ai_generated partial

lwIP: TCP connection to 192.168.1.100:80 timed out after 3 retransmissions

ID: embedded/lwip-tcp-retransmit-timeout

Also available as: JSON · Markdown · 中文
80%Fix Rate
90%Confidence
1Evidence
2024-06-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
lwIP v2.1.3 active — — —
lwIP v2.2.0 active — — —
FreeRTOS+TCP v3.0.0 active — — —

Root Cause

The TCP remote host is unreachable or not responding due to network congestion, firewall blocking, or device power state.

generic

中文

由于网络拥塞、防火墙阻止或设备电源状态，TCP远程主机不可达或未响应。

Official Documentation

https://savannah.nongnu.org/projects/lwip/

Workarounds

  1. 75% success Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count. 
    Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count.
  2. 70% success Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff. 
    Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff.

中文步骤

  1. Implement a TCP keepalive mechanism using tcp_keepalive() to detect connection failure earlier and reduce retransmission count.
  2. Add a fallback DNS resolution check before connecting: if host resolution fails, abort and retry with exponential backoff.

Dead Ends

Common approaches that don't work:

  1. Increase the TCP retransmission timeout in lwIP configuration (e.g., TCP_RTO_MIN) 80% fail

    Longer timeouts only mask the problem; if the remote host is unreachable, the connection will still fail eventually.

  2. Disable TCP checksum offloading on the network interface 95% fail

    Checksum offloading is unrelated to retransmission timeouts; the issue is network reachability, not data corruption.