JSFiddle - React, Tailwind, and code Playground
HTML
<label>Modem Number</label>
<input value=254 type=number min="1" max="254">
<button>Connect</button>
CSS
input:invalid + button{
pointer-events: none;
opacity: 0.3;
}
<label>Modem Number</label>
<input value=254 type=number min="1" max="254">
<button>Connect</button>
input:invalid + button{
pointer-events: none;
opacity: 0.3;
}