To soft reset your range extender after Linksys re4100w setup, follow these steps:
Find the Reset Button: usually a small, flush button on the back or bottom of the extender.
Press and Hold: With a paperclip or a similar thin object, press and hold the reset button for about 10 seconds.
Release and Wait: Release the button after 10 seconds. The extender's lights will probably start flashing, signaling a reboot.
Wait for Reboot: Give the extender ample time to complete the reboot. This may take a few minutes, but once the lights stabilize, the reset is done.