GPIO26 Sleep Mode on 3G/4G Base Hat

Hi all,
I am using a 3G/4G&LTE with Quectel EC25-EC to establish a PPP connection for my Raspberry Pi Zero.
I only need the connection for 20 minutes a day and would like to turn it off for the rest of it. Therefore, I set the GPIO Pin 26 to HIGH to cut the power. This results in a crash. I have to plug the power on the Raspberry to restart it. However, the Base Hat gets turned off before the crash. In addition to that, what I can do is turn the Base Hat off and on immediately after without crashing. Therefore, it must be an issue that the Base Hat is turned off. Is there some type of script running in the background?
Any help is very much appreciated!

Hello @olivier.staehli ,

What is the power cut sequence?
Do you turn off the PPP connection before setting the GPIO26 to HIGH?
When do you say crash, what exactly happens?

Did you try to set GPIO26 to HIGH without PPP connection or even without the module on it?