"Device Timed Out" error in Sidecar

I've been following this thread for a while as I too was having the same difficulty. I'm not sure if you were ever able to figure this out, but I just discovered that if you are connected to a network via VPN, then you will get this error. As soon as I shut down my VPN connection, I was able to get my iPad to act as a secondary monitor.

I spent some time going through several threads regarding this issue and what worked for me was not a solution that I could find anywhere. What worked for me was to go to Settings>Home Screen & Dock and make sure the check under "More" is selected. I had "Bigger" checked and as soon as I selected "More" my iPad connected immediately.

Try turning off the Today View feature on the iPad.

Go to Settings > Display & Brightness or Home Screen & Dock and toggle off Keep Today View on Home Screen

hope it works for you!

This totally did the trick for me. 2019 MBP 15in i7 and 12.9in ipad pro 2019. couldnt get it to connect after the first time. Tried signing in an out of apple id several time. turned off Today View and everything worked flawlessly.

Not sure if the issue still remains for you. But in case others need solutions..

Enter in your password at System Preferences > Apple ID > Overview.

It will say that your Mac needs to update Apple ID settings in order to allow you to fully use iCloud(or Apple)'s services.

I can assume that Sidecar is definitely one of its services.

Hope this helps.

So I tried some, but not all, of the above mentioned fixes without success. I decided to try disconnecting from WiFi and as soon as I did it connected the Sidecar. Sidecar stayed connected when I connected back to WiFi. 2020 13” MacBook Pro & 3rd gen iPad Air.

This worked. Had been using sidecar then upgraded to MacOs Big Sur and it disappeared. Had to sign in and out of iCloud on iPad to get it to show. Then would just come up with time out error. Switched handoff off on both then able to connect. Good news is you can then switch handoff back on!

I had to agree to updated terms and conditions on the iPad which was preventing it from airplay. I guess make sure your iPad is up to date and definitely on the same wifi. I have 2.4 and 5G, sometimes the devices join the alternate depending on location in my house. Good luck!

I had the same problem but after I signed out from my Apple ID on my MacBook Pro and re-signed in, it worked.

Turning off the Today View feature on the iPad worked for me.

I recently figured out that if my Macbook is connected to a VPN, it won't allow me to use Sidecar. UGH. It gives me the "timed out" error message

I tried everything on this page and none of it worked. What worked IMMEDIATELY was when I disconnected from the VPN I use to get to my work server.

Try it if you use a vpn regularly.

Making sure that both my iPad and Mac were connected to the same WiFi network solved this for me. Trivial oversight on my part.

I tried a LOT of the above suggestions. However what worked was having my iPad "Forget" the bluetooth connection to my MacBook air, and reconnecting them. THEN it finally reconnected!!!

I had this problem - plugging in a cable between the two devices fixed it. Kind of annoying, but at least it works.