I want to play the image on the web page automatically with the slider.
I set the playback speed as follows, but it is not reflected when I check with a browser.
Images will be played one after another at a tremendous speed.

I would be grateful if you could point out what caused it.
Thank you in advance.

var mySwiper = new Swiper ('.swiper-container', {
    loop: true,
    pagination: '.swiper-pagination',
    nextButton: '.swiper-button-next',
    prevButton: '.swiper-button-prev',
    autoplay: {
        delay: 3000, // Display time (milliseconds) until the slide changes
        stopOnLast: false, // Whether to stop automatic playback when the last slide is displayed
        disableOnInteraction: true // whether to stop automatic playback when a user swipe is detected
      <!-Additional required wrapper->
    <!-If we need pagination->
    <!-If we need navigation buttons->
swiper-container {
    width: 100%;
    height: 400px;
.swiper-slide {
    padding-top: 180px;/* For image position adjustment * /
    text-align: center;
    color: #fff;
    font-size: 30px;
    background-repeat: no-repeat;
    width: 1261px;
    background-size: cover;
    background-position: center center;"