From the GUI:
- Go to Security Profiles > GTP Profiles.
- Add or edit a GTP profile and select APN Filtering.
Set the Default APN Action.
- Select Create New to add an APN filter.
- Select an APN or APN Group.
Select one or more of the available Modes to indicate where the APN or APN group originated and whether the Home Location Register (HLR) has verified the user subscription.
- Set the Action to Allow or Deny.
- Select OK to save the APN.
- Select Create New to add more APNs.