JSFiddle - React, Tailwind, and code Playground

HTML

<table border="0" cellpadding="2" cellspacing="0" width="100%">
  <tbody><tr><td class="stxt2" align="center"><b>Refrescar Iframe - Snakenet</b></td></tr>
  </tbody></table>

<!-- Iframe  id="snakenet" está asociado para refrescar-->
<iframe id="snakenet" src="http://www2.cbox.ws/box/?boxid=2301954&boxtag=b3ba6e&sec=onliners"  marginheight="0" marginwidth="0" scrolling="yes" frameborder="0" width="100%" height="200"></iframe>

CSS

/* IGNORAR EL CSS */

table {
    margin: 10px 0px 20px 0px;
}
td {
    font: 12px "Helvetica Neue", Arial, Helvetica, sans-serif;
    color: #2D4063;
}
.stxt2 {
    background: #FFFFFF;
    border-top: 1px solid #DDD;
    border-bottom: 1px solid #DDD;
    color: #2D4063;
    min-height: 35px;
    display: table-cell;
    line-height: 35px;
}
b { color: #F97906;
    font-size: 18px;
}

JavaScript

// Iframe  id="snakenet" y getElementById('snakenet') deben tener el mismo nombre.
    
var iframe = document.getElementById('snakenet');
var refreshInterval = 1000 * 3; // Refresh every 30 seconds

setInterval(function() {
  iframe.src = iframe.src;
}, refreshInterval); 

//Diferentes intervalos de tiempo.

// 1000 * 5; // Refresh every 5 seconds
// 1000 * 60 * 5; // Refresh every 5 minutes
// 1000 * 60 * 10; // Refresh every 5 minutes
// 1000 * 60 * 30; // Refresh every 30 minutes