Changing Port Numbers

Ports serve as endpoints for communicating with other devices. Typically, conventional port numbers are used for major protocols, but devices that use these port numbers are vulnerable to attacks because these port numbers are well-known. To enhance security, your Network Administrator may change the port numbers. When a port number has been changed, the new number must be shared with the communicating devices, such as computers and servers. Specify the port number settings depending on the network environment.
To change the port number for proxy server, Setting a Proxy.
To change the port number for LDAP server, see Registering LDAP Servers.
Tap <Menu> in the <Home> screen.
Tap <Network Settings>.
If a screen for entering a System Manager ID and PIN is displayed, enter the System Manager ID and PIN, tap <Apply>, and press . Setting the System Manager ID
Select <TCP/IP Settings>  <Port Number Settings>.
Tap the port to change.

Learning more about the ports
<LPD>/<RAW>/<WSD Multicast Discovery> Configuring Printing Protocols and WSD Functions
<HTTP> Disabling HTTP Communication
<POP3>/<SMTP> Configuring E-Mail Communication Settings
<SNMP> Monitoring and Controlling the Machine with SNMP
Enter the port number using the numeric keys, and tap <Apply>.