Wi-Fi Repeaters: Why a "Signal Booster" Does Not Really Make Wi-Fi Stronger
Many home “Wi-Fi boosters” look successful at first: the phone shows full bars near the device, but speed barely improves, video still stutters, and games may even feel worse. The easy detail to miss is that the phone is seeing its link to the booster, not the quality of the booster’s link back to the router.
Most of these products are closer to a repeater / extender: the device first connects to the main router or upstream AP (Access Point) as a STA (Station), then acts as a downstream AP and rebroadcasts a wireless network for clients. It extends the place where clients can attach. It does not magically improve the whole wireless path from the router to the far room.