We are facing a weird issue after upgrading a DD4T project to Web 8.5 and using CIL provider. All the Content Delivery micro services as well as web application are present on a single AWS machine. It was working fine until we have restricted website and micro services by implementing VPN tunnel (same as present before upgradation) to access these micro services.
After implementing VPN tunnel website started rendering slow (5 times slow). To access the website url we are required to connect the VPN using Cisco AnyConnect VPN client and using NoSplitTunnel as security group. We are also using AWS Cloudfront service as a CDN to serve the web pages. We have verified the network settings, but didn't find any issue.
To find the root cause of the issue we have tried to access the content delivery service by changing security group to AnyVPN (in this case it is bypassing the security), in this case website started rending fast. Surprisingly, when we deployed the same website on another server, it is also rendering fast. So, issue is only when the website and micro services are installed on the same server.
We have further analyzed that
Sdl.Web.delivery.Linking.Impl.ComponentLinkImpl.GetLink method is taking approximately 5-6 times more time when website is hosted on the same server where micro services is installed compared to when website is hosted on separate server.
Although not sure if this issue is related to any impact of implementing VPN tunnel on CD services or caching but can anyone share if faced similar issue?