Thank you for posting this info. I was able to access the menu, which appears to not have an option to disable. But the fact that the menu is there, when people are acting like it isn't, frustrates me as a customer who went out of their way to pay for a WIRED unit. I'm trying to disable wireless also, because I don't want cancer. It appears there may not be a way to do this any longer. But months ago I had a wired Roku Ultra that would only emit signals upon startup, and then it would turn off after several minutes. It no longer does that, which means I have to unplug the unit. And unfortunately, that means I won't be able to use this device except for rare occasions.
It's pretty sad, frankly. Why can't we turn off the wifi? I want an answer from Roku.