Recently I configured a server within domain that wasn`t part of domain. It should host some services and be domain independent. To make everything easier for administration I enabled RDP connection for that non-domain server.
Initially it worked (I`m working from PC that is joined to domain) but results were mixed. Sometimes it worked, sometimes it doesn’t, when finally RDP connection to that server completely stopped working.
It got me pretty puzzled, until I finally realised that server I was trying to access is not part of domain.
So, on server that is not part of domain go to Control Panel | Windows Firewall | choose Allow an App or feature through Windows Firewall from menu on the left side |find Remote Desktop rule and check Public interface button. Confirm with OK and try again.
Non domain server treated domain computer like public interface, so that is the reason why it didn’t work. After enabling public rule computers from domain should be able to connect to RDP to non domain server.