The Express is a budget model that only can see or connect to wifi channels in the 2.4 GHz band. If your modem is using the 5GHz band only, your Roku can't connect. Most (all, maybe?) routers supporting GHz are dual band routers that also have 2.4 GHz, but it's possible the 2.4 GHz band is not turned on -- check your router's configuration.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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