Netbox Sync custom fields

The NetBox synchronizer exposes a fixed list of 13 fields on its Fields tab: Session Name, Host Name, Description, Tags, Manufacturer, Serial Number, Region, Site, Room, Rack, Asset Tag, Role, Device Type. Exactly one NetBox custom field is read `session_type` and it is hardcoded to select the entry type.
I would like to request the ability to map arbitrary NetBox custom fields to RDM entry fields, rather than extending the hardcoded list one request at a time.


In "NetBox Sync - Additional functionality", David Godin wrote:
> "To properly support this and avoid handling similar requests on a case-by-case basis, this will be addressed in a separate ticket focused on improving custom field support in the NetBox integration. This is not planned for the immediate term but remains under consideration."
That thread is now marked resolved, since the original requests shipped in 2026.1 and 2026.2.0, so the generic item no longer surfaces anywhere.

Use case

We track the assigned user of workstations and laptops in dedicated NetBox custom fields, first name, last name, account username. This previously lived in the NetBox `description` field and reached RDM automatically, since Description is one of the 13 supported fields. After moving it into proper custom fields, the information can no longer reach RDM at all.

Already ruled out

- Setting `CustomField1Title` on the synchronizer only renames the grid column; the value is never populated.
- Template variables resolve against the RDM entry, not the NetBox record, so `$CUSTOM_FIELD1$` returns nothing.
- The Custom (PowerShell) synchronizer works, but means giving up the maintained connector, the `session_type` handling and the built-in filters.