This is a GSM modem connected to a Pi zero 2 via a USB hub? Does the hub have its own power supply or is it powered from the USB port of the Pi? Please test with a powered hub, maybe the hub and modem are drawing too much current. Also, you can try to remove the following line in /boot/firmware/config.txt to see if that makes a difference:
dtoverlay=dwc2
This will switch from the dwc2 to the dwc_otg USB host driver.
This is a GSM modem connected to a Pi zero 2 via a USB hub? Does the hub have its own power supply or is it powered from the USB port of the Pi? Please test with a powered hub, maybe the hub and modem are drawing too much current. Also, you can try to remove the following line in /boot/firmware/ config. txt to see if that makes a difference:
dtoverlay=dwc2
This will switch from the dwc2 to the dwc_otg USB host driver.