Q:

Two computers in same network can't use any external RDP at same time

We are two users in the office which regulary use RDP to connect to client computers. But we have discovered a problem.
Whenever one of us is connected to a remote computer using RDP, the other user cant connect to any external computer using RDP.
And when one user disconnects from his RDP session, the other user is able to connect to RDP again.
I understand there are limitations on how many users that can connect to the same RDP session, but in this case we try to connect to completly different computers using RDP.
May this be a problem in our firewall, or what might cause this?

A:

This issue is almost certainly to do with the NAT setup of your router, essentially it's only letting the RDP return path talk to one internal IP.
There are a number of ways you could deal with this, without knowing your exact router and setup it would be hard to be specific but in this case I would warn away from trying to move the port used on the second external machine - it may seem obvious but RDP is a very well known and used protocol and that path would be more likely to cause problems in itself than resolve this on. Ultimately I suggest you deal with this in the more structured way of looking at your NAT config, put this detail on here by all means, and looking for a way to configure it better for this scenario. Worst case scenario however is that your router may not be able to do this and you may have to look elsewhere, thought I'd warn you up front.
Hope this helps.

