Questions about Denon Heos 7 Hs2

For a few months now, Spotify no longer works properly with my Heos system or Spotify no longer recognises Heos in my network. If I briefly turn the wifi off and on again on the iPhone, then it works again temporarily. Does anyone else have this problem?

What is actually going on. Have Heos products been discontinued? There is no decent shop on the Swiss market that still sells Heos speakers.

When exactly do I need the Heos Link. Unfortunately, my current Denon receiver does not have a built-in Heos Link. I wanted to buy a Heos 5 or 7. I can connect directly to the speaker via Bluetooth or? Can the Heos 5/7 be integrated into the existing WLAN?

Up to what humidity can the Heos 7 HS2 be used if it is installed on a covered terrace, for example? The temperature is specified, but unfortunately there is no information about the humidity.

I have a large room, about 55 sqm. Is one Denon HEOS 7 HS2 enough or would it be better to place two Denon HEOS 5 HS2 on different sides of the room? Thank you in advance for your answers.