I got a new Roku Streaming Stick+ and it updated itself to the latest version and almost everything works as expected. The screen mirroring from Windows 10 (2 laptops tested) is not working at all.
I followed all suggestions posted here and elsewhere on the internet without any luck.
So, I suspected that Windows 10 may be the problem. I tried screen mirroring with Amazon Fire Stick 4k and it works just fine so I have to to exclude Windows 10 (which by the way, I installed the latest updates for Network adapter and display).
The Roku Stick+ is detected and listed as a display in Windows 10 but when attempting to connect it fails after some time with the message: Can't connect.
At this time I put the blame entirely on Roku Stick+. Anyone having success with the same configuration?
I wish I did. My windows 10 laptop connected and projected fine (effortlessly) with my LG TV until Jan. 2020. I had a Roku Express connected too. Shortly after adding the Roku Streaming Stick+ I could no longer find the LG TV as a device and the TV showed no wifi connection any more. The Roku stick showed as a device and I could connect and project to the Roku fine until 2-3 months ago. Now mine does what you said. The TV looks like it is connected (asks to "allow") but nothing happens and after awhile I get a message that It can't connect. I'm also unable to navigate the screen to check or make another selection.
My frustration now is that I have the same problem with my iphone. Until about 2 weeks ago I could mirror my phone using the Roku Streamer and Roku Mirror app. I did at times lose connection and would have to restart the broadcast. In the past 2 weeks the phone connects to the TV but nothing happens on the TV when I start the broadcast. The Roku app sometimes closes (reverts to homescreen). My phone says it is broadcasting. I am still able to project pictures and video stored on my iphone, nothing streams. I usually am streaming a zoom meeting, but Ive also attempted other things.
I downloaded a new Miracast app for Roku and others but its cost $9.99 a month after a 3 day trial. I don't need that extra expense. I haven't tried it yet,
I successfully Mirrored screens from iPad Pro 12.9, iPhone 13 ProMax, and Dell XPS (Win 10 Pro OS), to a Roku Streaming Stick 4K (not +) for several weeks, until today. After much ping pong between Roku & Apple, I gleaned that somehow my Wi-Fi Network is preventing my devices from seeing the Roku stick, even though the Roku remote works just fine, and confirms the stick has internet access thru my Wi-Fi.
Leading up to this hard-failure, I did have similar disconnects from mirroring, but that seemed to have more to do with Bluetooth AirPods being connected out-of-sequence. Turning off Bluetooth on everything but my iPhone minimized strange effects.