Infinite loop when authenticated

What plugins do you have active?

On the network:
– Better WordPress Minify
– BP Auto Activate Autologin Redirect To Profile On Signup
– BuddyPress
– BuddyPress Multilingual
– BuddyPress Sitewide Activity Widget
– MultilingualPress
– Optimize Database after Deleting Revisions
– W3 Total Cache
– WordPress MU Domain Mapping
– Yoast SEO

Different plugins on each single site.

What plugins are active on the site where you are having this issue?

On that site, is your primary domain the mapped domain or the unmapped URL?

Also, when you are troubleshooting issues in your network you should deactivate caching plugins, minify plugins & CDN plugins.

I just network deactivated Better WordPress Minify, W3 Total Cache (and Yoast SEO).
Apart of the network activated ones, on the child sites are active:
– Cookie Law info
– MultilingualPress Addon: Nav Menu Icons
– Post Views Counter
– A simple plugin created by me to add custom taxonomies for posts (Qaxonomy)
– Restrict Content
– Search & Filter Pro
– Smartsupp Live Chat
– The Review Plugin
– WP Author Box Pro
– WPBakery Visual Composer

I just don’t understand completely your second answer: the problem are not in the main web site (instantcoach.me) but only in the mapped domains (allenando.it, tacticalpedia.com, tacticalpedia.pt). I hope it can help.
Thanks.

The problem remains even with these plugin deactivated.
I leave them inactive for your debug.
Thanks.

Do you have restricted content on the sites that are having this issue?

Yes, I have ‘Restrict Content’ plugin.

I saw the plugin in the list. What I was asking was if you were using it on the affected sites to restrict content?