Configure GA4 cross-domain measurement for an Aghanim hub and mirror domain

If your Aghanim setup uses both a primary hub domain and a secondary mirror domain, you should add both domains to Google Analytics 4 cross-domain configuration. Without this, GA4 can treat the mirror as a separate origin, which can break session continuity and attribution.

When this is needed

Use this configuration when players may move between two hub domains as part of the same experience, for example a primary hub domain plus a regional mirror domain.

How to configure it in GA4

1. Open Google Analytics.
2. Go to Admin → Data streams.
3. Select your Web stream.
4. Open Configure tag settings.
5. Choose Configure your domains.
6. Click Add condition.
7. Add each hub domain that should be treated as part of the same user journey.
8. Set the match type to Exactly matches for each domain.
9. Save your changes.

Example

If your primary hub is hub.example.com and your mirror is mirror.example.com, add both domains to the GA4 cross-domain configuration using Exactly matches.

Why this matters

This helps GA4 preserve attribution and session continuity when traffic moves between the main hub and the mirror domain.