Browsersync infinite loop that ends with unable to connect message

For many years I've worked with this setting of gulp and browsersync.

var gulp = require('gulp');
var sass = require('gulp-sass');
var browserSync = require('browser-sync').create();

gulp.task('browser-sync', function() {
    return browserSync.init({
        proxy: 'http://localhost:8888/myweb',
        port: 5555,
        noOpen: false
    });
});

It works as expected, but recently it has stopped rendering specific pages; for instance, it works in /page-1, but not in /page-2. The page with the problem loads fine from localhost, but not from the proxy of browsersync. The problem is that it loops infinitely and then gives an Unable to connect: Firefox (Chrome too) can’t establish a connection to the server at localhost:5555.

The pages that don't load have in common that those have a lot of lines of HTML. So my question is if browsersync has a limit in the HTML it can process? Or is something with my code?