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?