Electron with Third-party SIM won't connect anymore

Firmware
1

Initially, the Electron connected just fine for a full week, regularly coming out of deep sleep mode. Then, after being in deep sleep mode for 3 days straight, it now will no longer connect anymore. The firmware looks something like this:

#include "cellular_hal.h"
STARTUP(cellular_credentials_set("hologram", "", "", NULL));
int tinkerDigitalRead(String pin);
int tinkerDigitalWrite(String command);
int tinkerAnalogRead(String pin);
int tinkerAnalogWrite(String command);

void setup() {
Cellular.on();
Particle.keepAlive(60);

}

void loop() {
  if (millis() - lastConnectSample >= 8000) {
     lastConnectSample = millis();
     Particle.connect();
  }
  if (Particle.connected()) {
      Serial.println("connection established!");
      Particle.publish("particle/device/name");
  	locTime = millis();
      state = PRELOC;
      break;
      }

}
int tinkerDigitalRead(String pin) {
...
}
int tinkerDigitalWrite(String command) {
...
}
int tinkerAnalogRead(String pin) {
...
}
int tinkerAnalogWrite(String command) {
...
}

I'm quite puzzled by it, especially since it worked before when coming out of deep sleep, which should clear the RAM of the Ublox?

2

Can you also show your System.sleep() statement with its context?
AFAIK deep sleep does not (always) clear the radio module’s RAM.

3

Nothing special happens when the device enters deep sleep. I'll continue to monitor it, but it really is puzzling to me how last week it could go half a day in deep sleep and still connect just fine, but now it will just refuse to do so. Data-limit hasn't been reached either. I've reset the device a couple of times now, and also flashed the firmware a few times again, but it seems that I need to go through the setup process again before it'll work again.

case SLEEP:
  Serial.println("going to sleep now..."); 
  delay(500);
    System.sleep(SLEEP_MODE_DEEP, 86400);
  break;
    }
}

Also if you wonder, reading this made me believe that deep sleep clears the configuration in the UBLOX RAM. However, as I mentioned it worked before while coming out of Deep sleep, so I don't think it's very relevant to my problem.