Hello,
This error usually occurs when you have a poor connection to the game server. There are several things you can do to try to fix this error.

In order of severity, I would suggest trying
Clear the browser/client cache
Flush the DNS cache
Reboot the PC/device
Try a different device
Try a VPN program.

If you are trying a VPN, keep in mind that you may need to try several different VPNs to make it work to route you around the problem.

Unfortunately, when I say multiple VPNs, I don't mean two, I mean a dozen or more. You need to find a VPN that routes you around your problem, or the right server on a VPN that does it. Unfortunately, I cannot recommend a VPN for you, because I am not experiencing your specific problem and cannot troubleshoot it for you. This is a matter of trial and error.