A:Answer The Deco M9 Mesh system is considered Tri-Band because it utilizes two primary bands (2.4GHz and 5GHz) for device connectivity, but also uses a third, separate band (2nd 5GHz) exclusively as part of the system's Dynamic Backhaul. This provides means of efficient communication between Deco units, to provide optimal network bandwidth.
NOTE: This third band is not for device (phone, laptop, etc.) connectivity; it is solely a dedicated path of communication between the Deco units.
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TP-Link Support