线缆长度会影响网络速度吗？

## The Standard: 100 Meters

Ethernet (Cat5e through Cat8) is rated for runs up to **100 meters** (328 feet) at full speed. Within this limit, a 1m cable and a 90m cable perform identically.

## When Length Does Matter

- **Over 100m**: Signal degrades. Use fiber optic or a network switch as a repeater
- **Cat6 at 10 Gbps**: Only rated for 55m at 10GBASE-T (use Cat6a for full 100m)
- **USB cables**: Length limits are real — USB 3.2 Gen 2 maxes at ~3m passive
- **HDMI at 4K@120Hz**: Passive cables struggle past 3-5m

## What Actually Affects Your Speed

1. **Your internet plan**: The cable can't go faster than what ISP provides
2. **Router/switch quality**: Cheap switches bottleneck at Gigabit
3. **Cable category**: Cat5e maxes at 1 Gbps, Cat6a does 10 Gbps
4. **Damaged cables**: Crimped or bent cables cause packet loss

## Bottom Line

For home Ethernet runs under 30m, cable length has zero impact on speed. Focus on cable category (Cat6 minimum) and proper termination.