We had a Windows Server 2012 AWS Instance on EC2 that worked just fine, had a VPN connection to our office and we could RDP into it from our office.
However, I was in the process of trying to unblock the internet from inside the instance, and, in doing so, I followed some help articles from Amazon with what the default ACL and security group settings should look like. (port 80 and so on)
Did all of that, and, lo and behold, the next day, I completely lost access to the instance.
I've tried absolutely everything to regain access to it, even opened all traffic on both the one ACL and Security group we have both ways, and I still can't RDP into it anymore. At one point I noticed that something seemed to take effect in reverse, it was like, if I explicitly added an RDP rule or something, it would the adverse effect of blocking it but when I'd remove it it would be fine? (I don't remember exactly what the rule was unfortunately)
In any case, the fact that I'm even trying to allow all traffic in both directions on both layers of security and it still not working is just confusing.
I can't try any of the automated troubleshooting tools as unfortunately it wasn't set up as a managed instance to begin with, so I'm a bit screwed. I even tried EC2Rescue and even that fails...
Worse off, I even restored to a snapshot taken before any changes were made inside the instance and we now can't connect to even that...
All I did in the instance was try to disable the Windows Firewall, but I could still access it for some time after that, so, I don't know what actually cut access to it.
Unfortunately we don't have any support with Amazon and no one ever answers on their support forum...
I double and triple-checked everything, the routing table, the igw, the subnet, that the ACL and security group are assigned to the instance, went through multiple reboots, everything, but I still can't connect to it.
I can see the instance being just fine through the screenshot, but otherwise, we've completely lost connectivity to it.
Any help would be greatly appreciated as I'm just stumped.
Here are some screenshots: