The ‘Generic Hotspot’ profiles for AT&T will also update the TTL value for you which is not done when typing in the APN details manually using the ‘Generic’ Carrier Profile. If you need TTL set for your plan and use ‘Generic’ to manually enter the details you would need to enter ‘TTL’ (all caps, no quotes) at the Main Menu to set this manually. However, historically AT&T customers have not had to set TTL so this may not be relevant to you anyway.
You can refer to this KBA for APNs used by each preset Carrier Profile. Please let us know if increasing the WatchDog interval does not improve the issue you are experiencing.