Assign different IP range for bridged router attached to Orbi

[Redmumba]

I have a separate router (specifically, an old Airport Express) attached to my Orbi RBR750 that I restrict to 2.4ghz to run my IoT devices. Is it running in bridge mode. Is it possible to restrict the available IPs to a specific subnet that's different than my main router? Would this be a setting specific to the Orbi or the bridged router?

Thank you!

[CrimpOn]

I think the answer is "no".  The Orbi assigns IP addresses from one pool and does not know if something is 2.4G or 5G

On the other hand, Orbi has a feature called LAN Setup (see screen shot) which allows the user to assign specific IP addresses to individual devices by their hardware MAC address.  These IP addresses should be separate from the DHCP pool.

If devices intended to connect to the Airport Express are assigned IPs in the LAN setup, then when they connect that is what they will get.

[plemans]

Why are you wanting to do this?