@Vinoth Raj Sundaram Babu Firstly, apologies for the delay in responding here and any inconvenience this issue may have caused.
I would recommended to re-check the prerequisites once again and try to reset the Azure VPN gateway and let me know the status.
Troubleshooting: An Azure site-to-site VPN connection
Additional information: Enabling the ports on your firewall/router. Please go through this,
Sometimes antivirus can be incompatible with windows breaking IPSec connections.
When your VPN’s server and computer client are behind NAT devices, Then try to add a value to the windows registry. Follow this,
If the issue still persist, I wish to engage with you offline for a closer look and provide a quick and specialized assistance, please send an email with subject line “Attn:subm” to AzCommunity[at]Microsoft[dot]com referencing this thread and the Azure subscription ID, I will follow-up with you. Once again, apologies for any inconvenience with this issue.
Thanks for your patience and co-operation.
Hope this helps!
Kindly let us know if the above helps or you need further assistance on this issue.
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