We have a EC2 Windows Server set up and running in our VPC, connected to our network via a Juniper 5GT. This is working well, with the tunnel up and stable.
If I then join the server to our local domain, it appears to work - I can then log on using domain credentials, and use domain accounts when applying security to folders etc.
After I log out, if I give it around an hour, the box becomes unresponsive. I can't ping it, although a tracert goes all the way barring the last hop - so the tunnel is ok. I can't RDP into it. If I reboot it, then it works for a while before doing the same thing.
Un-joining it from the domain fixes the problem, and it stays up and stable. The event logs don't show anything obvious, at least to me.