This paper investigates the problem of channel selection in Wi-Fi 6E networks by modeling it as a congestion game, where access points (APs) aim to minimize their own co-channel interference (CCI) selfishly. We study the existence and the number of pure strategy Nash equilibria (PSNEs), the convergence to these equilibria, and the global optimal solution through best response dynamics (BRD). We provide theoretical proof for the existence and convergence properties and propose an algorithm for channel selection in Wi-Fi 6E networks based on the obtained results. Our findings suggest that the proposed BRD-based algorithm can achieve a global optimal solution in a distributed manner, offering a promising approach for efficient channel selection in Wi-Fi 6E networks.