We’ve been using a M5 tier shared mongodb cluster for one of our AWS account. There’s one EKS cluster which is connecting to this. Cluster is located in VPC-a. We had setup IP whitelisting(NAT IP) and Peering connection between Mongodb VPC and VPC-a. Everything was working without any issues.
Yesterday, we scaled up from M5( to M10(dedicated) but suddenly the applications/eks wasn’t able to connect to the database. But using the same credentials we were able to connect to the database via our jump server(different VPC). After a lot of debugging, just by coincidence deleted the VPC peering and then the applications/eks was able to connect the database.
We were unable to discuss and figure out what could’ve caused this issue. Had removed and re-added the NAT IP to verify by that didn’t fix it. Only after removing the peering connection it started to work.
Any explaination here?