Delete router ip in access point mode

I’m using volumio with a raspberry pi 3b+ as a mobile streaming speaker. The connection is done with wifi over the access point feature. The data is send via airplay from an Iphone.
If I want to receive audio data over cellular e.g. from spotify, that is not possible in default config, because the phone is connected to the wifi AP (which of course doesn’t have a connection to the web).

With the Iphone it is possible to change the wifi settings of the AP between automatic (dhcp), BootP and manual. If you choose manual, you can set a static IP and delete the router IP. That procedure is described in this link:
With that setting it is possible to receive data over cellular and send the audio over wifi with airplay to the raspberry.
Is it possible to do those settings on the raspberry/in volumio?

Indeed it is working the way I described, but if I’d like to connect a new device I have to copy the settings/the IP and type that manually into the corresponding fields. I think it doesn’t make sense, that the AP of volumio pretends to be a real connection to the www. Would make more sense to delete the router IP in default, so every connected mobile device is able to use cellular data in parallel with sending audio over wifi.
Is it possible to implement that in future builds? Is there any possibility to do that manually e.g. over ssh?

Kind regards,

Can’t you create a hotspot on you mobile device, and configure Volumio to connect to that SSID?

It should then try and connect to your hotspot, or if its to available create it’s own Volumio hotspot that you can connect to…

I don’t know if that is possible. I think if I want to use airplay to stream audio to volumio, the phone has to be in a wifi.
But I’d like to connect various devices anyway. I would have to connect the raspberry to every hotspot first.

Yes, that is the solution I’d like to use. When volumio opens an access point and the devices wouldn’t see a router IP, you could use cellular to receive data and send them via wifi/airplay to volumio. That wifi connection would behave like a bluetooth connection.