SSH was suddently blocked on Router TG74n v3. Every attempt to connect from exterior network is rejected. This can be pretty bad if it is the only way to access from outside to local network.
The SSH connections on port 22 were being dropped by firewall.
To solve the problem, you have to change rule which is causing this problem. By editing the rule, you can change the action from
The following lines first deletes the rules and then add it again, but changed with the pretend parameters:
firewall rule delete chain=forward_fire index=1 firewall rule delete chain=forward_fire index=3 firewall rule add chain=forward_fire index=2 name=SSH srcip=184.108.40.206 serv=ssh log=enabled state=enabled action=deny firewall rule add chain=forward_fire index=3 name=SSH serv=ssh log=disabled state=enabled action=accept
A discussion about this problem can be found here:
http://forum.meo.pt/t5/Equipamentos-Internet/porta-ssh-22-outbound-bloqueada/m-p/59591/highlight/true#M13917 (Local copy)