Problem is, if voltage fluctuates than this problem happens.
First, Quectel must accept that problem and try to solve it.
In one thread @Kyson says send AT+CFUN = 0 than send AT+CFUN=1 but it does not work too.
This problem is not a problem that customer can solve. I do not know why Quectel side insist to deny this problem. It is not a problem that is little.
This is very important problem. Think it a little, I sell a device than it does not connect internet. Because it does not detect sim card.
You can also create that problem at office too. While device is working fluctuates voltage and than that happens.
So, guide to solve that problem by software.