Sharp LC-55LE643U Operation Manual page 44

If you cannot connect to your
wireless home network during
guided setup:
If you are not getting 3 or
more signal-strength bars
above your wireless network,
adjust the location of your
Roku Streaming Stick and/
or wireless router. Make sure
there are no obstructions, like
cement walls, between your
Roku Streaming Stick and your
wireless router.
Make sure you select the
correct wireless router name
on the "Wireless" screen.