DIR-620S  Wireless N300 Router with 3G/LTE Support and
USB Port
User Manual
Configuring via Web-based Interface
Parameter Description
Modem IP address 
verification
Move the switch to the right to let the router request the actual IP 
address from the modem in case modem's IP address changes before 
expiration of the previous one.
When all needed settings are configured, click the APPLY button.
Page 105 of 238