unknown problem

[wh1ter0z]

hello ahmad i have a sim800l and esp8266 nodemcu lolin

i connect sim800l like this -> sim800l(rx,tx) to nodemcu(tx,rx)

and when i connect gnd to nodemcu i cant send any AT commands

when i disconnect that gnd i can send AT commands and not get any response

for getting responsse from sim800l
i have to disconnect gnd and send AT command then connect fast a gnd to get response

(with connected gnd recive response from sim800l , without gnd i can send AT command and i not recive any response )
can you help me ?

nodemcu esp8266 lolin
sim800l
gps neo6m v2 - also this module leds not blinking

i dont know why

need your help

COM4.2022-01-18.09-26-23.mp4

Disconnected gnd and send AT then connect gnd then i got response