You need to login into your routers web page (typically, 192.168.1.1)
and find the DHCP manager. There, you will see a list of all the devices
connected to the wifi network and can assign static IP addresses.
I found that Spotify has its own volume control. Maybe that is the case
for video call app - the volume in the app might be low while the volume
of the speaker is high?
There is one IR sensor from Aqara (P1) that I can already see in the GH
app and it has a "Voice notification" option. No other automations
available, though.