drop vpn S2S

@Paulo Silva

Thank you for reaching out.I understand you would like to know the probable cause of VPN connection drop you observed on your S2S VPN in Azure.

Determining the exact cause of the issue will not be possible without looking at the backend logs, so the recommended step here will be check the diagnostic logs for your Azure VPN gateway and see if you are able to observe any errors.

The probable cause of the connectivity issue her can be:

• Validate if the on-prem device used is validated for Azure VPN Gateway. The list of validated devices is documented here.
• Check whether the on-premises VPN device has the perfect forward secrecy feature enabled. The perfect forward secrecy feature can cause disconnection problems. If the VPN device has perfect forward secrecy enabled, disable the feature. This is documented here.
• As you observed two drops in the VPN connection in last two months, creating a support request will also help troubleshoot in this scenario as a support engineer can access the backend logs to determine if there was any other cause of this failure. Please let me know if you do not have a support plan.

Just in case if it helps you can also explore the Dual-redundancy active-active design of Azure VPN which is the most reliable design option is to combine the active-active gateways on both your network and Azure.

Hope this helps! Please let me know if you have any additional questions. Thanks!