I would recommend you to check if the appliance can connect to the update servers. In the GUI, go to System Administration > Upgrade and Update Settings. Take note of the Routing Table that is used for updates (Management or Data).
Once you have the above info, go to the CLI and test the appliance to see if it has connectivity to the update/upgrade servers.
(select the interface - Management if Management Routing Table is used for updates; P1/P2 if Data is used for updates)
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...