Multisite infinite redirect loop

If I’m not mistaken you have to set the cookie paths and domain, like it is explained here:

• Resolving The WordPress Multisite Redirect Loop

by Tom McFarlin. In a nutshell:

In your wp-config.php file, add the following lines of code:

define('ADMIN_COOKIE_PATH', "https://wordpress.stackexchange.com/");
define('COOKIE_DOMAIN', '');
define('COOKIEPATH', '');
define('SITECOOKIEPATH', '');

And do so just before the line that reads:

/* That's all, stop editing! Happy blogging. */

Once done, the redirect issue should be resolved.