Short answer

ESP32 SNTP never gets a sane time. What should I check?

  • SNTP needs a working Station IP and UDP 123 outbound. Captive portals and strict firewalls block it silently.
  • Set timezone and sync wait correctly. Reading wall time before the first sync yields 1970 and breaks TLS.
  • Use a reachable NTP pool for the region. A hard-coded dead server looks like ‘SNTP is broken’.
  • Products without RTC still need SNTP after every deep power loss before MQTT TLS.

中文

短答

ESP32 SNTP 对不上时间，查什么？

  • SNTP 要有可用 Station IP，并能出站 UDP 123。门户热点和防火墙常会静默挡住。
  • 时区和等待同步要设对。第一次同步前读墙钟时间会是 1970，TLS 先挂。
  • 用本地区能到的 NTP 池。写死一台失效服务器会像「SNTP 坏了」。
  • 没有 RTC 的产品，深度掉电后仍要在 MQTT TLS 前再跑 SNTP。