Casting (screen mirror) fails on PC/Laptop caused by Antivirus Firewall.
There are many posts here and on the www in general indicating that screen mirroring (casting, connecting) from a Laptop or PC fails to connect to the Roku. The connection starts, then about 1/3 of the way through, the connection status bar on the Roku connected TV just stops. After a while the connection fails on the PC/Laptop.
Given that your Roku is properly configured for screen mirroring,
The cause may be the Firewall on your PC/Laptop (I.E. Antivirus App).
To check if this is your issue, FIRST try turning off the Firewall in your Antivirus. How to do this depends on your Antivirus App.
If that works and your PC/Laptop now connects, THEN you might proceed with the following which should allow you to leave your Firewall active and still connect/cast/screen mirror to the Roku:
I added a range of IP addresses allowed and now my PC/Laptop will cast/connect and screen mirror to my Roku - with the Firewall active. There may be a similar process with other Antivirus Apps.
Disclaimer. I do not know if this action is totally safe. Proceed at your own risk. However it should be better than just disabling your Firewall.
This is for my current version of McAfee:
Open McAfee and select the My Protection Icon (four dots in a square or other method)
Under Protect your PC, select Firewall
Scroll down and select My Network Connections.
At the bottom of the list click on Add
Add this range of IP address Start 172.16.00 End 172.31.255.255
Add this range Start 172.29.243.224 End 172.29.243.255
Be sure to select Home Network - that should still protect those IPs from external connections while allowing on your home network.
Save the work, turn your Firewall back on and you should be good to go.
I have a Roku 3810X Streaming Stick + software version 10.5.0. Until several weeks ago, I had no problem using screen mirroring to connect my laptop to the Streaming Stick +. Now, my laptop tries to connect and the splash screen shows for a second then the "Starting video from" screen opens and about 1/3 of purple progress bar appears (screen photo below). The Stop video button and the Options button do not work. At this point the only thing I can do is return to the Home screen. After about a minute my laptop says "Couldn't connect to your device" and the screen reverts to the previous screen. Nothing has been changed by me. I've done everything but reset the Roku. I'd appreciate help getting this fixed. Thank-you.
On my Dell XPS 17 9700 running Windows 10 Pro Version 21H1 I click on the Notification icon on the lower right. I click on the Connect button and a list of available devices comes up. I select the appropriate television and the top of the computer screen says "||Connecting your device". Prior to this I started Roku 3810X Streaming Stick + software version 10.5.0 to any screen and when the Connect button is clicked the splash screen shows for a second then the "Starting video from" screen opens and about 1/3 of the purple progress bar appears (screen photo above). The Stop video button and the Options button do not work. After about a minute my laptop says "Couldn't connect to your device" and the screen reverts to the previous screen. I haven't changed any settings on the laptop or the Roku. I've tried restarting the laptop to no avail. I hope that explains it. Thanks for your help.
I am and have been having the same problem on my roku stick. Worked fine and about a month or so ago it stopped. Checked settings on laptop and restarted stick several times. It is also set on always allow screen mirroring. Get the same screen original poster entered. Please advise.
I am and have been having the same problem on my roku stick. Worked fine and about a month or so ago it stopped. Checked settings on laptop and restarted stick several times. It is also set on always allow screen mirroring. Please advise.
My screen mirroring will not connect to my Roku TV. I have tried updating my iPhone and my Roku TV, restarting my Roku TV, turning Airplay and the screen mirroring settings off and back on, resetting all devices on Airplay, and every other tip that I have found online. Nothing seems to work. It’s been this way for months. Please help!
I have not gotten a definitive answer but I found that a youtube video has a control that says "Play to TV". It's a square with the wifi symbol in the corner and it works. Maybe someone can figure out why that works and Connect in Windows 10 doesn't.