An engineer has deployed Cisco Aironet 3800 Series APs with switches that support 802.11bz on existing CAT-5e cabling. Which value is the maximum distance supported to achieve up to 5 Gb speed?

30 meters is well under the supported distance for 5GBASE-T on CAT-5e and does not correspond to any defined limit in the 802.3bz specification.

40 meters is also below the 70-meter maximum for 5 Gbps on CAT-5e and is not a defined distance limit in the 802.3bz standard.

IEEE 802.3bz defines 5GBASE-T, which achieves 5 Gbps over existing CAT-5e infrastructure up to a maximum channel length of 70 meters - beyond that distance the cable's bandwidth characteristics cannot support the higher modulation required for 5 Gbps. At shorter runs or with CAT-6/6A cabling the full 100-meter reach is available. This 70-meter limit is the key constraint for deploying multi-gigabit PoE APs such as the Cisco Aironet 3800 on legacy horizontal cable runs.

90 meters exceeds the 70-meter ceiling for 5GBASE-T on CAT-5e; 2.5GBASE-T can reach up to 100 meters on CAT-5e, but achieving 5 Gbps requires either higher-grade cabling or staying within the 70-meter constraint.