Hello,
Did you try to disable Auto APN and set it up manually.
An Access Point Name (APN) is a gateway between a GSM, GPRS, 3G or 4G mobile network and another computer network. Depending on the contract, some operators may require you to enter the APN just to complete the registration to a network.
Additionally, a public IP address is necessary to access to device via WAN. In case your Public IP address is dynamic, you can use DDNS.
More information can be found here
Best regards,