A child’s tablet shows a buffering spinner while large golden packet arrows leave one router toward several household screens. something needs explaining

Why does WiFi slow down when busy?

One video plays smoothly. More family devices join, and pauses appear. Nothing broke. What became scarce?

Nearby devices take turns using a shared radio channel. The available airtime does not multiply for every screen.

Three family devices wait on visible golden packet queues; arrowheads show one router sending a packet outward on one route at a time.

Tap to add devices. The same router and airtime clock must send fewer packet dots along each route.

Change the stream count. More screens share the same router, and the model computes 100 divided by active streams.

Tap demand. Packet arrivals stay the same, but the screen begins buffering when the video asks for more.

This channel has 90 units. Every active video needs 18. All streams share equally in this model.

The channel carries 90 units. Each stream needs 18.

Which joining stream is first to miss its share?