No 'Access-Control-Allow-Origin' in webGL Unity Multiplayer

I’m using “Network Lobby” asset for unity and trying to make webGL build with using WebSockets. When I create a game or get a list of servers I get the following error:

XMLHttpRequest cannot load No ‘Access-Control-Allow-Origin’ header is present on the requested resource. Origin ‘my_domain_name’ is therefore not allowed access.

Is it a problem on the server or on the client? And how can I solve it?

@mox1342 I don’t you are able to use sockets with WebGl. At least not yet. You might have to use the WWW class or the UnityWebRequest class. I’ll leave the source from where I read it, hope it helps.