AT+CFUN=1 returns error


I have a strange problem with one of my SARA N211 board. After been running great for a couple of months it suddenly stopped sending data to our server. When debugging the board I found out that AT+COPS=1 gave ERROR in return. After removing the simcard and putting it back again gave the same problem. Then I tried to put in another simcard and the board started working again. Then I tried putting the old simcard back again and the bord worked.

So, swapping simcards back and forth once solved the problem. Has anyone had the same problem or does anyone know what the problem may be?