ESP8266 Not Booting When Powered from VIN with 5 Volt But does when USB powered

Hi Guys

I have built a simple project using a 8-Channel 5V Relay Board and an NodeMCU ESP-12 module loaded with Tasmota.

I am powering the device from a board mount 5 Volt DC PSU connected to the GND and VIN pins.

The problem I have is that the board does not boot up when powered via the DC PSU. I need to press the Reset button on the board after supplying power to get it booted.

When connected via the USB port however, all works 100%.

I know the board initializes when the relays hits once and the 2 LED's on the NodeMCU flashes once on power up.

The unit needs to be cased up and should power to it fail and get restored later, start up without any user intervention.

Even without the relay board connected I am experiencing the same problem.

Any ideas?

ESP8266 runs on 3.3V