Device configurations or software can sometimes cause connectivity to fail. This includes the application software and the GSM module/ chipset and its firmware as well.
If this SIM and device combination has worked before but not anymore, make sure you have not changed any configurations. Update the firmware to a previous version.
If it is a new device you are using for the first time with the SIM/eSIM and you are experiencing issues, check the below items:
Are you registered to the network?
Are the data settings entered correctly?
Is the APN entered correctly? Does the APN match the active connectivity profile on the SIM?
Try restarting the device
If eUICC functions are not working properly