HTACCESS and redirect on screen resolution?

Question

PHP

How to make a redirect to the mobile version of the site if the user comes from a tablet (portrait) and leave it on the main page if from a tablet (landscape)?

Answer 1

980 - the width of the browser window, of course, you should choose the optimal one.
And call the function, as you prefer, either by loading or by onresize.

function redirect() {
    if (window.offsetWidth<=980) {
        window.location.replace('/mobile=1');
    }
}

Answer 2

It is impossible to do this at the web server level, because the server does not own the device information when it receives an HTTP request.