MAC

In the same meeting room, Wi-Fi signal may look full, but pages load slowly, video calls freeze, and ping latency jumps around. The first reaction is often “the signal is bad.”

But strong signal does not mean the air is free. Wireless devices do not have dedicated cables. Many clients, APs, Zigbee, Thread, or other 2.4 GHz devices may be competing for the same airtime.

At that point, experience is affected not only by RSSI and SNR, but also by a lower-level contention rule: who may transmit, when they may transmit, and what happens after a failed attempt.

When a host already knows the destination IP, and maybe even the next hop, the packet does not leave the NIC as an IP packet first. What lands on the wire is an Ethernet frame. Problems like “same subnet but no connectivity”, “ARP never gets an answer”, or “DHCP broadcast went out but nobody replied” are not mainly Layer 3 problems. They usually fail earlier, at the Layer 2 hop.