X server comes with built-in support for remote desktop because of its client and server architecture. In Fedora Linux systems, X server is disabled on the network by default. That means the X client programs residing on the same host only can connect to X server. If enabled, typically X server runs on port 6000.
To enable X server on the network, search for DisallowTCP in /etc/X11/gdm/gdm.conf file and modify it to look like the following.
You may have to either restart the X server or reboot the system to get the settings in to effect.
If you still not able to connect to X server, check if it is really enabled on the network by looking at the list of actove ports in listen mode using netstat command.
If X server is enabled for network connections, you should see something similar to the following.
If you see some listen socket on port 6000 and still having problems in connecting to X server, most probably iptables firewall should be dropping the incoming connection. If so, disable firewall on port 6000.