Adding on to what @porter mentioned, hexnode only marks a device as inactive if it is configured in General Settings. It is usually enabled by default, so that might be why it seems automatic.
If you go to the admin tab and open General settings, you will find the inactivity settings. There you can decide if a device should be marked as inactive and set the time period for it. For example, you can say a device becomes inactive after 2 days or 10 hours of not checking in.
If you want something even more organized, you can set up a dynamic group. It keeps itself updated without any manual steps.
Set it up like this:
- Column group: Compliance info
- Column: Device status
- Comparator: is
- Value: Inactive
After you set this, all inactive devices will automatically appear in that group. If a device becomes inactive later, it joins the group on its own. If an inactive device becomes active again, it leaves the group automatically.