AWS. Trying to make 2 machines be network available

I have two machines on AWS. Both of them are on the Default VPC, the same subnet, the same IP range, but I'm unable to make them network reachable. Both machines have Windows Server 2012. One of them can see the other one through the browser (I have IIS installed on one of them and the security group allows them to see be seen through TCP/IP). But whenever I try to share files and resources between them, even with the same accounts with the same passwords, they can't seem to see each other. I've read through some AWS documentation and it seems I'm doing everything according to the docs, but I'm pretty sure I'm doing something wrong in the AWS console. Anyone have any suggestions?