Help connecting android app to local router that doesn't have internet

I have a HA instance running on a Dell Wyse 3030. I have it jacked to a router without internet. So far, my HA android app only connects to the router’s loal HA IP when I deactivate data on my phone (even though I have the phone set to keep connected to the wifi that doesn’t have internet)

I would like to be able to point my HA app to the local IP without having to turn off my phone’s data every tome. How do I go about it?

Does your phone have a setting to switch to mobile (cellular) data if it can’t reach the internet via Wi-Fi? On my Samsung it’s called intelligent Wi-Fi. Turning this off may work.

Yeah, I have the intelligent switching turned off and have the setting on that keeps me connected to a network even if it doesn’t have internet. to no avail.

but I’m sure there would surely be a solution, right? how do movie hoarders access their movies locally? surely, they have a convenient way to access their local servers? Problem is, i’m not a networking guy, i’m not sure if I’m posing the query in the best way possible

android will not connect to wifi that has no data.