TP-Link TL-MR3420 User Manual page 12

RESET:
There are two ways to reset to the Router's factory defaults:
1) Use the Factory Defaults function on "System Tools -> Factory Defaults" page in the
Router's Web-based Utility.
2) Use the Factory Default Reset button: With the Router powered on, use a pin to press
and hold the Reset button (about 5 seconds) until the SYS LED becomes quick-flash
from slow-flash. And then release the button and wait the Router to reboot to its factory
default settings.
TL-MR3420 3G/3.75G Wireless N Router
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