We eliminated the issue by switching to esptool (https://github.com/espressif/esptool/releases).

I'm facing the same issue on some custom boards. Any updates on this?

Hi experts, I face an issue that happens when connecting to a remote host over WiFi using LWIP. It happens every couple of transmission cycles seemingly randomly after a wakeup from deep sleep or cold boot. The error returned from connect() is -1, with an errno of 128, indicating that the socket is ...