Sidecar connection problem [duplicate]

Solution 1:

I had this problem setting up a new computer. For me, what fixed it was going into Settings > Accounts > iCloud and checking KeyChain.

It said I needed to update my account security and prompted me with a few security questions. This seems to have indirectly solved the problem; perhaps some minimum standard of security was not upheld and was causing quiet failure.

Unfortunately, I'm guessing that this won't solve everyone's problems as it seems to be a pretty generic message as mentioned above, just thought I'd add my solution to the pile for everyone who's going down the list and trying everything.

Solution 2:

I suspect that this is a very generic error message and that not everyone who is experiencing it is encountering the same root cause.

I just experienced this error after successfully using Sidecar all day long at work.

After I came home, I logged onto my work's VPN to check on something and, after some amount of time, Sidecar disconnected. When I tried to reconnect it, I got the same "The device timed out" message.

On a hunch, I disconnected from the VPN (in the FortiClient app that my employer requires for VPN access) and Sidecar worked again.

Bottom line: using a VPN can cause this symptom.