Connection drops ESP8266-1 AP Mode

Is it about channel or so, I'm just not sure, but my android phone keeps losing wifi connection and immediately connect back continuously - therefore I can't transmit any data.

Here is my configuration :

  sendCommand(F("AT+CWMODE=2")); //change mode and reset afterwards
  sendCommand(F("AT+RST")); // reset module
  String strCommand = F("AT+CIPAP=\"");
  strCommand += AP_IP;
  strCommand += F("\"");
  strCommand = F("AT+CWSAP=\"");
  strCommand += AP_SSID;
  strCommand += F("\",\"");
  strCommand += AP_PASSWORD;
  strCommand += F("\",1,3"); //configure ap ssid and password
  sendCommand(F("AT+CIFSR")); // get ip address
  sendCommand(F("AT+CIPMUX=1")); // configure for multiple connections
  sendCommand(F("AT+CIPSERVER=1,80")); // turn on server on port 80i
  sendCommand(F("AT+CIPSTO=600")); //set timeout to 10 mins

And logic:

if (esp8266.available()) // check if the esp is sending a message
    if (esp8266.find("+IPD,"))
      int connectionId = - 48;

Which channel should I use? Is it overlapping (I think channel 1,6,11 don't overlap).

PS: After resetting arduino, I can connect and transfer data with no issues. This happens when I reset eeprom and set up an AP again (from switching STA mode).