Hi @Kiransuryavamshi-1246,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
We understand that you are facing issues with your site-to-site vpn connection.
- Please follow this troubleshooting document and see if could identify the cause of the issue.
- Please consider the additional troubleshooting steps below to further investigate this problem.
- Could you please verify if the pre-shared key shared in both environments is correct?
- Please verify the address space mentioned in the Local Network Gateway and ensure it is not overlapping.
- Please use the below document to troubleshoot the VPN gateway issues using diagnostic logs. Refer: https://zcusa.951200.xyz/en-us/azure/vpn-gateway/troubleshoot-vpn-with-azure-diagnostics
- Please make sure you have not used the NSGs on your gateway subnet level. The NSG on the gateway subnet are not supported. Associating a network security group to this subnet might cause your virtual network gateway to stop functioning as expected.
- Perform continuous pings from the on-premises network to Azure and then gather packet captures.
- Please check IKE logs. It would be helpful to check these logs while conducting the ping test.
- Refer: https://zcusa.951200.xyz/en-us/azure/vpn-gateway/troubleshoot-vpn-with-azure-diagnostics#IKEDiagnosticLog
- To resolve the problem, first, try to reset the Azure VPN gateway and reset the tunnel from the on-premises VPN device. Kindly let us know in the comments below if the above helps or you need further assistance on this issue. If it was helpful, please click "Upvote and Accept Answer" on this post to let us know. Thanks, Sai.