What can be preventing Remote Desktop access to remote computer

I am trying to RDP to a client host 192.168.3.20 in my office network from home.
I connect to the office network via a VPN 172.17.0.17 (untangle VPN) and can successfully RDP to the AD Win2k8 R2 server 192.168.3.5, but somehow I can never connect to the client host's RDP service.

Within the RDP session with the AD server, I can RDP to the client host.

The thing is, I used to be able to do this. And the last time I did this was when my RDP client is on Vista and the AD master is Win2k3. Right now, my RDP client is on Win 7 and AD master is Win2k8 R2. I don't know if the system defaults changed or what.

I have already set in group policy to allow RDP and remote adminstration exceptions in the default policy. I also have domain windows firewall turned off in the group policy. Also set allow response to ICMP echo requests but no ping response. What else could be preventing the access?

The client host I am trying to access runs Apache, VisualSVN, MySQL etc all of which cannot be accessed. I am guessing it's to do with ports. But why? Firewall is disabled!