Not working setNetMode & checkSignalQuality together

Dear DFROBOT Team,

I am facing a conflict between the checkSignalQuality() and setNetMode() functions in my project. When I use the checkSignalQuality() function before calling setNetMode(), the setNetMode() function fails to set the network mode and repeatedly returns "Fail to set mode". On the other hand, if I call setNetMode() first and then attempt to use checkSignalQuality(), the signal strength returns "404", indicating that it is unable to capture the signal strength.

Here is a simplified version of the code I am using:

int signalStrength;
Serial.println("Get signal quality......");
delay(1500);
signalStrength = sim7000.checkSignalQuality();         // Check signal quality
Serial.print("Signal strength = ");
Serial.println(signalStrength);
delay(500);

Serial.println("Set net mode......");
while (1) {
   if (sim7000.setNetMode(sim7000.eGPRS)) {            // Set GPRS mode
       Serial.println("Set GPRS mode");
       break;
   } else {
       Serial.println("Fail to set mode");
       delay(1000);
   }
}

Are there any known issues or conflicts between checkSignalQuality() and setNetMode() that might cause this behavior?
Do you have any suggestions or debugging tips for resolving this conflict?