MC7455 - Works properly a few minutes and deregistered


I own a MC7455 mode install in a WE826 router with firmware R00ter.
The modem is in QMI mode “same problem in MBIM”.
It connects well sometimes and after several hours or sometimes a few minutes, the modem is deregistered and can not reconnect. When I make the AT + CPIN command, the modem returns me CM ERROR. For the modem to reconnect, I need to type the AT! RESET command.
According to you, does the problem come from the SIM card, the SIM card slot or the modem?

Thank you