SideCar Issues

Check all information here, Use your iPad as a second display for your Mac with Sidecar - Apple Support

I am using Sidecar with my MacBook Air (2019) and my iPad Pro 11.

Danny350 wrote:

hmm, I am not sure how to check that. However, that might be the problem as I am working from home.

Did your organization provide you with an app to install—Cisco AnyConnect is one of the VPN clients known to commonly block Sidecar—and will usually also require you to specify organization-specific access credentials to gain admittance onto your organization’s internal network. If so, you’re very likely using a VPN. And VPNs can be configured to block all local network traffic, including Sidecar.

Danny350 wrote:

Yes, they sure did. That has to be it. Thank you!

When you next disconnect from the VPN, see if Sidecar then starts working.

That’ll confirm the diagnosis.

A discussion with your IT organization about local network access might then be reasonable, though the IT folks may or may not decide to authorize local network access while connected to the VPN.

Are you running with a VPN client enabled? Some of those will block access to Sidecar.