Step 1: Open a web browser and type the IP address of the D-Link DI-634M into the address bar (default is 192.168.0.1). Press Enter.
Step 2: The default username is admin (all lower case) and the default password is blank (nothing). Click on OK.
Step 3: Click on the Home tab at the top and then click on WAN on the left side.
Step 4: Select the WAN port you desire to be in backup mode. Set Connect Mode to Backup.
Step 5: Click on Apply to save your settings.
Note: Upon completion of the following steps, when the primary WAN connection fails your backup connection will enable itself. If the primary WAN port is connected, the backup port will remain disconnected. The backup WAN port will only be enabled if the Primary WAN port it is backing up is disconnected. Load balance will not work if a WAN port is set to backup mode.