solved it! "iCloud encountered an error while trying to connect to the server" for windows 11 laptop.

I ran into the same issue recently and found a different solution for PC's that use Killer Wifi Network cards on Windows 10/11 machines. Given that I run a wired network I disabled the Killer network via the system configuration (msconfig). Following a reboot, icloud was functional again. The solution was originally posted here. cannot connect to icloud from windows 11 … - Apple Community

That is VERY good advice - although for me - just deselecting / deactivating IPV6 on each computer solved the problem - I didn't have to change to Google DNS servers...

What is odd is that for the past year we have had no issues accessing icloud.com from any computer and any browser - just in the last couple of weeks we were not able to access it - perhaps a windows or driver update?

Thanks again! and just repeating what you suggested that worked for us below:

You can disable IPv6. IPv6 is a newer version of the internet protocol, but it can sometimes cause problems with iCloud. To disable IPv6, follow these steps:

1. 1. Open the Start menu and search for "Network Connections".
   2. Right-click on your network adapter and select "Properties".
   3. Click on the "Advanced" tab.
   4. Scroll down to the "IP Settings" section and uncheck the box next to "Internet Protocol Version 6 (TCP/IPv6)".
   5. Click on "OK" to save your changes.

I have the same problem but with a macbook pro with Sonoma 14.2.1

I think it's a network related problem. If I switch network, personal hotspot for example, I can login into icloud.com and I can send iCloud email from Mail app.

I tried disabled ipv6 from my router and from mac using

sudo networksetup -setv6off "USB 10/100/1000 LAN"

but it's not working.

I tried the IPV6 solution first, but is did not work for me. Maybe I should have rebooted. Thanks for the comments.

I disabled the service called Killer Network Service on both of my laptops, and it solved the problem.

Thank you very much! =)