Wifi ony working with serial monitor connected

[Kasperdelasopa]

Hello,

i have designed a custom board, which doesn't have much.

The key "features" are CH340C to upload a sketch and 4 connections to connect a temperature sensor with I2C.

I'm able to upload the program and i'm able to execute it WITH a serial monitor connected to monitor debug output.
But once i connect it to a power only power supply the device starts but seems not to be able to connect to to wifi.

I tested that by adding a flashing led to every WiFi connect attempt.

It also doesn't work, when i use the PC USB cable to power it when i don't open a serial connection to it. It can be reproduced, that is works fine with a serial connection, an does not connect to WiFi once i only use a USB cable to power it.

I was wondering if it is my sketch so i tested it on a WEMOS EPS32. In that board the sketch runs without an issue in the same power supply. ==> Therefore my sketch seems not to be the issue, as it only doesn't work on my custom board.

Unfortunately i have no idea what might be the issue. I have searched in Google with ever possible combination of "ESP32" "no WiFi" "Serial monitor"

For the auto-program-circuit i used the 818-40 transistors, but i don't think so as upload works without an issue.

I upload the schematic here:

https://ibb.co/Gsw6YTh

[ESP_Sprite]

Are you sure your ESP32 is not resetting (because of a brownout)? Looking at your schematic, I'd try putting some 10uF caps on the 3.3V side as well, see if that helps.

[Kasperdelasopa]

Hey,

I'm sure it does not reset.

I tested also a more simple sketch, where it setup wifi and loop over a led blink procedure... setup passes and the device blinks in the defined behavior. That's for serial monitor and for power supply. With the serial monitor the wifi connects and i see it in the router. On power supply the device never show up on the router, but blinks.

About the 10uF cap: There is allready one parallel to a 100nF cap (right upper in schematic)