Why Amateur mesh networks such as AREDN are built from repurposed consumer Wi-Fi hardware, so they run on the amateur allocations that overlap the unlicensed Part 15 bands: 2.4 GHz (13 cm), 5 GHz (5 cm) and 900 MHz (33 cm). Operating as a licensed amateur on the portions of those bands allocated to the amateur service allows higher power and gain antennas than Part 15 permits, and the modified firmware keeps the channels inside the ham segments. Mesh needs wide bandwidth for routed IP data, which only the UHF and microwave bands can supply.
Watch out HF digital segments are far too narrow, just a few kilohertz, to carry the megabit-rate IP traffic a mesh node routes, and the 60-meter channels are single-signal USB or narrowband data channels shared with federal users.
Mesh = hacked Wi-Fi gear: 2.4 GHz, 5 GHz, 900 MHz, the ham bands that share space with unlicensed services.