What is the calDAV url for an iCloud account

Everytime i synchronise my iCloud calender there is a red mark on the right of ‘iCLoud account’. It does not synchronise with my iCloud account. Some months ago this was not the case. I use the iCloud calDAV url : https://caldav.icloud.com/ Does anybody know what is the problem ?

You have the right URL. It’s the only one I’ve ever used.

I find occasionally I have to renter my (or a new) Apple “app specific password”. The one created within iCloud.com on the PC.

Try that. Just had to do it, but to fix a recurring prompt for userID/Password for the calendar/contacts account.

My network mode is ‘public’ and I do not use any DNS and use DHCP for the network settings. Anybody an idea what could cause the not synching with iCloud caldendar ?

The thing is that I also renewed my accound. deleted the ICloud account and entered again. I even renewed the App-specific password of my Apple Id account. Could it be that I have to force a Port to open in my Windows 11 firewall. For example : port 80 ?

There was an issue with older versions of eM Client 8.2 on Windows 11 beta, where CalDAV would not sync because of the .NET version used. We bundled the latest .NET with eM Client, so this issue should not be there with recent 8.2 releases.

What version of eM Client are you using?
You will find that in Menu > Help > About.

But something like this could also happen if you have disabled TLS 1.2 on Windows 11.

I have currently the beta of version 9. Version 9.0.1142.0. Where can I check TLS 1.2 ?

Version 9 is not an issue with .NET

TLS is a Windows setting, so you would need to ask Microsoft.
Some users try to adjust the settings, and when enabling TLS 1.3, they mistakenly enforce it so the others are disabled. Probably you would know if you changed that.

But that may not be the issue at all.

Can it be a port problem ? For example a port that is closed ? I use the default settings of the windows 11 firewall

The Windows firewall by default won’t affect this unless you have changed it.

Only you will know if you have made changes to the OS to disable certain options. If you just install Windows 11, install eM Client and setup the iCloud account, it will connect.

If it doesn’t then you may have the wrong credentials for the iCloud account, some hardware or security app is restricting the connection, or the account may have issues on the server.