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