Client Port / Connections from other clients, Client to Client Source Exchange

You can change this port in Preferences -> Connection -> Client Port
This port has to be forwarded in a router. Changing this port in Preferences you must also change the forwarding in the router

Client Port / Connections to other clients, Client to Client Source Exchange

4662 is the default port, but other clients may have different settings. Change the remote port to any when configuring a firewall

Clients source asking / extended eMule protocol, Queue Rating, File Reask Ping

This port has to be forwarded in a router. Changing this port in Preferences you must also change the forwarding in the router.
If you are not able to forward this port check the disable box in Preferences -> Connection -> UDP Port

Clients source asking / extended eMule protocol, Queue Rating, File Reask Ping

4672 is the default port, but other clients may have different settings. Change the remote port to any when configuring a firewall

Connection to server

4661 is the default port of a server. Many server use different ports. Configuring a firewall the remote port again changes to any.

Servers using the default port 4661 TCP (see #5) automatically set their port for source asking to 4665 UDP. If a server uses a different port in #5 the corresponding UDP port is set to [Connection Port + 4]. For firewalls the remote port here is any.