My NB-IoT board de Luxe occasionally seems to loose its connection with the T-mobile network. It's the board we got during the training on Nov 3rd, so with a SARA N211 and the new 6.57 firmware. Derived from the demo sketch we used during the training I wrote a sketch that repeats sending data every 30 seconds (AT+NMGS=25,"0bb6107503ed004eab330008b1e348454c4c4f2046454c4958").
What I observe when the connection is lost, is: "AT+CGATT?” returns a “0" and the “AT+CSQ” returns signal strength “99.99”.
Sometimes the connection can be restored by issuing "AT+COPS=1,2,”20416” and wait until connection is restored ("AT+CGATT?” return a 1). Sometimes I even have to switch off/on the radio.
Does this sound familiar to someone, and how to solve it in a robust manor?