Calling with Sim800l stops Arduino

[ECE9]

I have 5V 4A common power source for both SIM800l and Wemos D1mini. A diode is reducing the voltage for SIM800l and it's working fine. It calls me and I can answer it. After the call SIM800l acts normally, led blinking is normal. But the problem is Wemos. It stops working right after it sends the call command and wont recover without power off.

My code:

if (payload[0] == 'a') {
    Sim800l.begin(9600);
    delay(2000);
    Sim800l.println("AT");
    updateSerial();
    delay(500);
    digitalWrite(LED_PIN, LOW);
    delay(900);
    digitalWrite(LED_PIN, HIGH);
    delay(900);
    digitalWrite(LED_PIN, LOW);
    delay(900);
    digitalWrite(LED_PIN, HIGH);
    delay(300);
    Sim800l.println("ATD+ 04005863112;");
    Serial.println("I call now");
    updateSerial();
    delay(10000);
    digitalWrite(LED_PIN, LOW);
    delay(900);
    digitalWrite(LED_PIN, HIGH);
    delay(900);

It blinks two times but not the third. Need to power off & on to get it back to work. (led_pin low turns the led on). SIM800l calls me and works fine.

Is the problem with the code or is the gsm sending some interference to Wemos? Or could there be some power drop for Wemos when SIM800l starts the call? If there is a power drop, shouldnt it recover as from normal power off/on?

Blurry image attached of the setup.