How to avoid early timeout while function autosaves?

Question

I currently have the following code. The function is supposed to auto-save text the user inputs on the screen for 7 minutes (420000ms) without the user pressing a "submit" or "done" button. I have two screens like this, with the let counter having a different value in the other screen.

The issue is that when I run this on the server and in html, the screen times out on its own before the 7 minutes is up. Same for the other screen with this code. Does anyone know why? Is there something wrong with the function? Is there any alternative?

let counter = 8; //named differently in other screen

this.saveInterval = setInterval(() => {
  // Pull out the text field
  // Save the value into the collected data
  this.data["inputValue" + counter++] = document.getElementById("RPsun").value;

  // Submit the form automatically      
if (counter >= 8) {
  this.submit();
}, 420000);

this.saveInterval; // save