I made a simple two-button interface in html. These buttons send a GET request to a local server.

It works perfectly on browsers on both Windows and MacOS, as well as Android devices...but not in any browser on iOS (iphone/ipad).

Here is the function:

function toggle() {
let xhr = new XMLHttpRequest();
xhr.open('GET', './RemoteCommands/?SetCuelistPlayToggle=', true);
xhr.setRequestHeader("Cache-Control", "no-cache, no-store, max-age=0, must-revalidate");
xhr.onload = function (e) {
  if (xhr.readyState === 4) {
    if (xhr.status === 200) {
      console.log(xhr.responseText);
    } else {
      console.error(xhr.statusText);
    }
  }
};
xhr.onerror = function (e) {
  console.error(xhr.statusText);
};
xhr.send();
}