Cables, Wi-Fi, and the Physical Layer: What is Actually Carrying Your Bits
Networking from Scratch (lesson 6) — copper Ethernet categories with real distance limits, PoE class wattage, single-mode vs multi-mode fiber, the connectors and transceivers you will physically handle, the three Wi-Fi bands and why 2.4 GHz is a swamp, and how to recognise common physical-layer failures fast.