This Matomo plugin adds to your installation a new dimension called visit_subnetwork then reports visitor counts coming from private networks.
Settings are easily configurable by Matomo's General Settings administration page. You have two choices.
Private Address Space from RCF 1918, such as localhost 127.0.0.1, and IANA pre-defined networks 192.168.x.x, 172.16.x.x, 10.x.x.x.
Configure your custom subnet rule by writing a regular expression matching the IPv4 addresses of your other intanet mapped on the web (called extranet).
This plugin is a complete refactoring adapted and mantained for actual Matomo, of the first IntranetSubnetwork that was published for Piwik 2.x.
Installation
Just install by Matomo's Marketplace, or grab latest code from the Github repository.
Translations

License
This free software is licensed under GNU General Public License v3+
Support
You can ask for support and your feedback is appreciated at plugin's issue center on Github.
Changelog
Version 5.x
- Weblate translations community powered
- Added support for Matomo 5.x
Version 4.x
- fixing #10
- Merging of community translations
- Added Weblate support for community powered translations
- Updated regular expression rule matching RCF 1918 Private Address Space
- Added support for Matomo 4.x
Version 3.x
Version 2.x
- Added Default Subnetworks configuration field. It's a checkbox you can use to include sandard networks measurement.
- Added Web Administration configuration field. You can use it writing your custom Regular Expression for catching Subnetworks IPs.
- Features imported from IntranetSubNetwork old plugin.
- Mayor bug fixing.
- Rewrite from scratch using console generator helpers.
Can I define my own intranet space?
Yes, you have a settings field inside General Administration page. You can choose pre defined IANA standard RCF Private Space and you can define your personal regular expression matching your custom network.
What is a regular expression?
Regex Are a sequence of characters that specifies a pattern.
How do I can test my regular expression rules?
There are useful tools online, such as Regex101