Hello @daniyyel ah, ok. So the correct documentation is here. Have a look at the code examples in Quick Start Guide to see how the M5IOE1 needs to be programmed to turn on power etc. The function is called SIM7028_EN() and first turns on power then resets the modem. Thanks Felix

I FOUND THE SOLUTION!!! After diving into deep of operating system I figured out a possible solution which worked for me: I had a usbserial.kext laying in /Library/Extensions/ and I figured out that it was also a WCH driver I deleted usbserial.kext and restarted the Mac again => no success I deleted CH34xVCPControlDriver.kext and CH34xVCPDriver.kext in /Library/Extensions/ and restarted again I installed another driver: FTDIUSBSerialDextInstaller_1_4_7 and had to confirm SIP integrity In system preferences -> security I had to enable access for the FTDI driver and saw another process pending named something with Quinheng As I remembered that Quinheng has something to do with WCH I ticked this process too and restarted I installed CH34xVCPDriver.pkg V1.7 again and restarted => no success I plugged in a CH340G device and suddenly a /dev/cu.wchusbserialXXX port appears in my Arduino IDE and is working with my CH9102 device Plugging out CH340G device continues /dev/cu.wchusbserialXXX working Hope that this solution will work for other people too!