IPSec Site-to-Site VPN Local Subnet Becomes Unreachable due to Inactivity

Hello. We have an IPSec Site to Site VPN tunnel established with Oracle Cloud Infrastructure (OCI). There are two local subnets at SOPHOS XG end (x.x.x.x and y.y.y.y). At OCI end there is only one remote subnet (z.z.z.z). Now our users are at x.x.x.x from where the OCI is accessed 24/7. But on the other hand, the y.y.y.y subnet is of SSL VPN. So it's used randomly. Now we observe that when there is no network activity from the Y subnet, after a while IPSec tunnel becomes unavailable via SSL VPN. We have to disable/enable the IPSec tunnel and after that OCI becomes reachable from Y Subnet (SSL VPN).

We searched for a solution or workaround but couldn't find any. Would love some feedback or suggestion.



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[edited by: Erick Jan at 1:01 PM (GMT -8) on 6 Feb 2023]