Synergy client won't connect, despite open port?

• You have to run the same version of synergy for both version.

• Check the hostname.

• Check if you do not have any firewall on windows/linux that is generating issues.
• Change the port 24800 by 8081. That works for me.
• Remember both have to listen the same port.

Good luck!

In linux, I needed to use this command like described earlier:

sudo iptables -A INPUT -p tcp --dport 24800 -j ACCEPT
sudo iptables -A OUTPUT -p tcp --dport 24800 -j ACCEPT

I also added the computer name (client and server) in configuration, exact same names at both of them. (Ex: computer-client, computer-server).

Except for having the correct iptables rules mentioned all around here, be sure you apply the rules in the correct order within your iptables configuration as well. Apply them BEFORE the rule that drops/rejects the packets. That was something I needed to figure out :-).