I am encountering this problem on both a Roku Premier and Roku Ultra (connected with ethernet).
I have other Roku devices in the house that don't seem to cause the same issue.
The device(s) that cause the issue are located next to the wireless router, could that be a contributing factor?
If you want to disable WiFi Direct, simply disable Device Connect (that's Roku's term for WiFi Direct):
Settings/System/Advanced system settings/Device connect=disabled
You wont be able to do so unless and until any/all WiFi Direct (Point Anywhere/Voice) remotes are either unpaired (either by "forget this remote" or by pairing it to another Roku, etc), or not "In Use" (by using another remote IR-only).
Unfortunately that configuration doesn't seem to stop the wireless broadcast, at least as of when I reported the issue. I've confirmed this with wifi scanners on my mobile.
The only reliable solution in the past was to disable from the secret menu, which is now not available
Wireless <> WiFi <> WiFi Direct
To be clear, disabling Device Connect does disable WiFi Direct, which is what the title of your feedback asked to be able to do.
Not sure what you are referring to as a "wireless broadcast", but once Device Connect is disabled, you will not be able to find/detect the Roku using WiFi Direct (or any other functionality that relies upon it, such as Miracast or Hotel & Dorm Connect).
You might want to re-name/re-title your OP to "Option to disable all wireless/WiFi output"
Fair enough, i edited the original post subject. The desired behavior would be to disable the broadcast of a wifi signal, which used to be available in the Secret menu.
I was able to eliminate my wifi interference issue (when I was using the wifi Roku remote that comes with Roku Ultra+, it was disrupting other wifi signals in my house) by switching to a IR-only remote [purchased on Amazon]. Using the IR-only remote still fully controls the Roku Ultra+, but I don't have the wifi interference.
I did not change any Roku settings.
I use an IR logitech remote. Before i just gave up and wrapped in faraday fabric, the wifi signal on the rokus used to cycle in strength as if they were broadcasting for a wifi direct device on a interval. I was able to 'temporarily fix' this by doing what you suggested, and turn off all the wireless features I could from the settings menus. However this would get reset on reboots, upgrades, etc....so it was quite annoying.
Now i just stopped having to tinker with it by wrapping in faraday fabric and hoping the CPU doesn't overheat. So far its been good - with a few warnings here and there. If I had a backup roku device, I would crack them open and attempt to remove the radios...but the faraday fabric is doing a good enough job.
Just wanted to add that while turning off Wireless <> WiFi <> WiFi Direct settings sounds like a solution, its not a sticky config. If I wasn't clear earlier, i'll add now that this config gets overridden often with auto-updates and system reboots. Before using shielding faraday fabric, I'd get my entire network crashing down while i'm working, or streaming video, or my kids streaming remote classroom stuff. Having the uncertainty of network quality over wifi is terrible...so a solution that works for an nondeterministic period of time isn't that great.
Sure - "wireless off" needs to survive reboots/restarts/firmware updates (but not network connection resets or factory resets).