How to change the LAN IP address ?

From the Main menu select the following menu options:
Configuration
Interfaces Set-up 
LAN Set-up
IP Set-up
IP address "xxx.xxx.xxx.xxx" [xx]

How to change the WAN IP address ?

From the Main menu select the following menu options:
Configuration
Connection set-up
Remote site set-up
Remote Site summary 
Note: Take note of the active id or the Remote Site alias that you wish to make changes to.

Edit remote site
Enter the id or the Remote site alias from the Remote site summary.

Protocol set-up
IP parameters
Local IP address "xxx.xxx.xxx.xxx" [xx]
Peer IP address  "xxx.xxx.xxx.xxx"

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If the 3rd character in your firmware version has the letter "p"  (ie., 52pxxx), then you are using the non-VPN
 firmware version. Change the LAN IP Address or WAN IP address as shown: 

How to change the LAN IP address ?

From the Main menu select the following menu options:
Configuration
LAN Set-up
IP Set-up
IP address "xxx.xxx.xxx.xxx" [xx]

How to change the WAN IP address ?

From the Main menu, select the following menu options:
Configuration
WAN set-up
Remote site set-up
Remote Site summary 
Note: Take note of the active id or the Remote Site alias that you wish to make changes to.

Edit remote site
Enter the id or the Remote site alias from the Remote site summary.

Protocol set-up
IP parameters
Local IP address     "xxx.xxx.xxx.xxx" [xx]
Peer IP address      "xxx.xxx.xxx.xxx"