Domains That Must to be Accessible for Site Tracking
The following sites must be accessible for MonsterInsights to work:
The first is used for measurement protocol, the next 3 are updates and reports functionality, and the last one is reports from GA as well.
If your site is on a private network you’ll probably need to contact your server administrator of your company’s private network and make connection from the site possible to those site.
If your web hosting company has a firewall, you’ll need to contact the web host to whitelist those domains.