I was using 5v from the main board ( FTDI Serial connector) to feed my esp-32 board and it wasn't working. it did work with a previous wemos d1 board, though
So it seems the 5v power supply from the board is not very good ( I suspect it does not provide enough power)
Therefore I used a 12v to 5v converter and now it work perfectly
This explains why on the documentation a 12v to 5v converter is used to feed the wifi board
Originally, I though this was because the previous board layout did not have the 5v on the connector, but now it seems it was correct all along!
Hope this helops somebody