What happens when MDM vendor certificate expires? There is no way to renew the MDM vendor certificate,you just have to create a new one.
After I create a new one, the devices have to be re-enrolled.
Is there a way I can avoid re-enrollment of devices?
I want to know what happens to the enrolled devices when the MDM vendor certificate expires?
If APNS certificate expires you have to enroll the devices. APNS certificates are valid only for an year.

Here is how you can renew APNS .

https://www.hexnode.com/mobile-device-management/help/renew-apns-certificate/