There are some known settings for Orbi.
On Android instead of putting in the core IP address try 255.255.255.255 somehow the broadcast address works, weirdly.
Netgear Orbi Routers
If you’re making use of an Orbi router, we recommend unchecking Disable IGMP Proxying in your router’s settings. This setting can interfere with the ability for Roon Remotes to connect to the Roon Core.