Greetings,
Did you try resetting you VPN gateway in this case? If not, you can give a try. Resetting an Azure VPN gateway is helpful if you lose cross-premises VPN connectivity on one or more Site-to-Site VPN tunnels.
Note: When you reset the gateway, it reboots the gateway, and then reapplies the cross-premises configurations to it.
Here Is the article that describes about steps that must be placed before resetting a VPN gateway.
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