How to configure RBS50 to expose media server on existing router network

[spartabantam]

I've followed the instructions on https://kb.netgear.com/31218/How-do-I-configure-my-Orbi-router-to-act-as-an-access-point to setup my Orbi to an existing router.

This router previously was my wifi network, and is also wired to my NAS which hosts media player/sever/fileshare etc.

My Samsung TV could quite happily see this NAS with basically zero setup.

I've now connected my Samsung TV to the Orbi wifi network and it is unable to see my NAS share.

Any clues on what I need to to to either my existing router (HG633) or my Orbi setup to help with this?

[CrimpOn]

When the Orbi is set to Access Point (AP) mode, the primary router makes all IP assignments.  Was the NAS set up with specific IP address in the HG633 router?  Actually, since neither the television nor the NAS are likely to "come and go", my preference would be to set up IP addresses for both of them in the HG633.  I do that for my printers as well.

Do you have a way to scan the local network and figure out the IP address of all your devices?