I have a situation that multiple Cisco VPN client 3.5.1 at branch office that need to connect via NetGear Router through Cable Modem and then connect back to our HQ that terminated on VPN 3000 Concentrator.
The VPN will established then drop the connect within minutes, if more then one user try to connect.
Could anyone shed some light on how is this might happen? What is alternative solution to solved this? Given the branch has limited budget that purchase a 2611 is prohibited.
This is usually seen as a limitation with your PAT device (Netgear in this case). Actually Linksys used to have the same issue which was resolved in the later OS versions, which was the way it handled packets on UDP port 500. Kindly make sure you are running the latest Netgear OS and get in touch with the Netgear support for an answer in this regard, as this is an issue with the intermediatary device.
Upgrade your concentrator and your clients to at least 3.6.1. Enable NAT-T on your concentrator and nat transparency on your clients and see if that works. You will need to make sure that UDP port 4500 is allowed through any firewalls.
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...