Sim800L-v2.0-network-problem

I am having trouble to get Sim800L-v2.0 to work. I believe that I am supplying the necessary amount of current (5.0V, 2.1A máx power source, using solid copper wires - circuit photo). The Net LED keeps blinking every second, meaning that it was unable to connect to the network.

Serial monitor readings:

15:57:32.630 -> AT
15:57:32.630 -> OK

16:02:15.391 -> at+cops=? 
16:02:23.775 -> +COPS: ,(0-4),(0-2)
16:02:23.775 -> 
16:02:23.775 -> OK

16:02:29.075 ->  AT+CPIN?
16:02:29.075 -> +CME ERROR: SIM not inserted

16:02:51.008 -> AT+CREG?
16:02:51.008 -> +CREG: 0,0
16:02:51.008 -> 
16:02:51.008 -> OK

16:02:59.639 -> AT+CSQ
16:02:59.639 -> +CSQ: 0,0
16:02:59.639 -> 
16:02:59.639 -> OK

16:08:09.354 -> +CFUN: 1
16:08:09.354 -> 
16:08:09.354 -> OK

Inspecting the readings, it indicates that the sim card is not inserted at all, which is odd. While searching for some tips on the subject, I did encounter one or another claiming that the problem might be related to the incorrect capacitor used in the circuit module, not really sure though...

Country: Portugal
Sim card netw.: Altice

Any ideas to solve the issue? Is it a module problem, or am I missing some steps? Thanks in advance!

Code used:

#include <SoftwareSerial.h>
 
#define TX_PIN 10
 

#define RX_PIN 11

SoftwareSerial serialGSM(TX_PIN, RX_PIN);
 
void setup() {
  
  Serial.begin(9600);
  while(!Serial);
   
  
  serialGSM.listen();
  serialGSM.begin(9600);
  delay(1000);
   
  Serial.println("Ready.");
}
 
void loop() {
  
  if(serialGSM.available()){
    Serial.write(serialGSM.read());
  }
  
  
  if(Serial.available()){    
    serialGSM.write(Serial.read());
  }
}