Volumio app cannot connect to the Volumio server behind a router

Hello all

I have installed Volumio 3.378 on an old laptop and i’m quite happy with its performance. It is connected through Ethernet to my main network (, where NAS, AVR, etc. are located.
My WiFi is not on the same subnet, since i use a TP_Link router for such purpose. Its WAN port is on while its LAN and so all devices connected through WiFi are on

My problem is that the Volumio app, either on iPad or Android connected through WiFi, cannot find the Volumio server, so as to control. Control apps of similar devices, like Denon AVR, Heos, etc. work and can connect to the respective devices which rely on the same subnet with Volumio.
Through a browser it works, so it is not an IP routing issue.

I have enabled IGMP proxy, etc. but still nothing,
Can you please help to overcome this issue and advise on the required actions?