A wireless extender may offer a strong signal to the player while using a weak or busy connection upstream. Signal bars describe the nearby radio link, not the capacity of every hop between the stream and the screen.
Trace the two links
Consider both router-to-extender and extender-to-player connections. A unit installed at the very edge of router coverage may repeat an unreliable connection. Moving it closer to the router can be more useful than placing it closest to the television.
Check the operating mode
Some devices support a wired access-point mode as well as wireless repeating. Those modes have different performance characteristics. Read the model's instructions before changing settings, and keep a copy of the previous configuration to avoid losing the network.
Measure the viewing experience
Compare startup and interruptions through the extender, directly to the router, and over Ethernet if possible. Keep the content constant. If direct access works better, the extra wireless hop deserves attention before blaming the streaming account.
