We have an app that uses SignalR to talk to scanner drivers locally that has been in production for a couple of years working on IE, Chrome and Firefox, which do not have a prob
I had the same issue. While Ajax calls to a page on the same domain were working in every other browser, in Edge they wouldn't. Opening the url used for the Ajax call in a different tab would give the correct results. Adding the piece of code to the page serving the Ajax calls fixed it somehow... The code is in C# but maybe this will give a general idea how to fix it in other languages.
if (Request.UserHostName == "127.0.0.1")
Response.AppendHeader("Access-Control-Allow-Origin", "*");