When you use a USB / TTL CH340 adapter it often happens that the start is blocked
The leds ( gadgets )with their "low value" 330R resistors interfere with the RX/TX line
For this CH340 adapter if you remove the led diodes s from the adapter it no longer
blocks the start
What does this mean?
When you connect the adapter before connecting the power supply it blocks the start
*
Oh so it's a problem of the TTL
Yes EXACTLY, mine is a CH340 the first usb serial I snapped on Amazon a while ago, and it works great with my Tasmota/ESPHome crappy devices 
And this is the reason it should be at 5 seconds for the boot time, otherwise it's almost impossible to get there on time (and still on 5 secs it's pretty tricky if I don't put the USB on time) 
By the way @hecatae also reported this behavior a time ago for a similar router. He did a even more trickier stunt to fool the issue: he disconnected GND and plugged it back after powering the router. I found that just not plugin the USB was simpler. Now here you have the solution to the issue 
PS: Maybe I can snap a FT232RL that I find on Amazon relatively cheap also, may it work better?
Hi.
I bought this recently. Works like a charm.
https://www.amazon.fr/dp/B07DJ4T7WK?psc=1&ref=ppx_yo2ov_dt_b_product_details
I know for the CP 104 but what I say is to use the CH340 when you only have that
It was a reply for this.
New img ( remove the 3 leds )
