1. Which role is the OBS Studio setup you're working on assuming in the NDI context, sending, receiving, or both?
2. Which segment are you trying to move NDI over?
When OBS Studio is in the sending role, by way of the Tools/DistroAV menu item (and likely as a filter as well), the interface you select in the Settings/Advanced/Network/Bind to option. That will likely also dictate which interface you will stream over as well. Beam does a much better job by keeping this information within the plugin, separate from OBS Studio's network settings.
Hope this helps.
--Katt. =^.^=