At what length do Ethernet cables drop to lower speeds?

Ethernet cables reliably transmit their rated speed up to 328 feet (100 m); beyond that, signal loss and timing issues cause degradation. Cat5e and Cat6 maintain 1 Gbps across the full length, while Cat6 supports 10 Gbps only to about 180 feet, requiring Cat6a for 10 Gbps up to 328 feet. For runs exceeding 328 feet, use a midpoint switch or replace the excess with fiber optic links, and consider PoE power limits.