VPN tunnel down after reset for ()DescriptionThese alerts indicated the VPN tunnel between our data-centers and your public IP address is either DOWN, or the VPN pairs are NOT the same.Your VPNs in ServiceNow are identified as <DATACENTER_ID>-<ServiceNow-public-IP>_<Customer_public_IP>We need to validate on both YOUR end as well on the ServiceNow end and when this type of alert occurs, the AHA or the Advanced High Availability feature becomes temporarily unavailable. What is a VPN? A virtual private network (VPN) creates a private network from a public internet connection. VPN services establish secure and encrypted connections. It is important to know the required maintenance and changes on the VPN configuration need to be done on BOTH sides. For alternatives, please read the following blogs:You Don't Need a VPN Pt I - LDAP Integrations, User Data Imports & the MID Server solution and You Don't Need A VPN Part II - LDAP Integrations, User Data Imports, & the Internet solution CauseThis alert happens when the system is not able to establish a VPN tunnel between ServiceNow and the customer public IPs. The causes can be several: VPN tunnel is downThere is some maintenance activity going on with the tunnelsThe VPN tunnel status was decommissioned so alerts are being raised. Please confirm if you need us to remove the VPNs on our sideFirewall restricting the VPN tunnels. Please confirm with your Network administrators to validate the VPNs public IPs have been added to the list of accepted IPs on your firewall.ResolutionEnsure with your network administrators the VPNs are are UP and running.If the VPNs are UP, we need to validate the correct encryption domain ranges (IP addresses defined in a tunnel) have been set. Please confirm the values expected. They are on CIDR format and look like e.g. 209.173.53.167/20.If the firewall has restrictions, please update it with the list public ServiceNow IPs: KB0679421 - Questions about Inbound and Outbound firewall rules needed to the instances and datacentersIf the problem has been resolved, we would leave a day to check it is stable, then move the alert for closure.If the tunnel is not being used, please make sure that you inform ServiceNow regarding the decommissioning of the tunnel. Please confirm if any maintenance activity or planned changes from your side. More information on VPNs is our docs: Virtual Private Network (VPN)If you do not need the VPN tunnel anymore and need to decommission it, please see KB0547274 for instructions. Additional InformationImpact: Please note VPN Tunnel down issue may generate another alert related to LDAP Server and some of the users may not able to access the instance if you are depending on VPN Tunnel for LDAP integration. Please let us know if your network team requires assistance to expedite the resolution of this alert.