I'm struggling with my network. It worked fine a couple of weeks ago (and has worked well for a long time) – I have no idea what has happened.

My router from my internet provider is in bridge mode and connected to a Deco M9, which is in router mode.

Our house has four floors, and the M9 router is located in the basement (I can’t really move it up into the house). Additionally, I have two M9 units in the basement, one M9 on the ground floor, one M5 on the ground floor, one M9 on the first floor, and one M9 on the second floor.

I also have a large Sonos setup with three wired devices connected to the M9 router (via a switch – otherwise, there wouldn’t be enough ports on the M9).

I also have a NAS with my large music library wired to the switch.

The problems:

When I measure Wi-Fi speeds throughout the house, it looks fine – between 100 and 300 Mbps depending on the distance from the M9 router (and close to 500 Mbps download speed when using Deco’s own test of the Deco router). Overall, I’d say the coverage is pretty good.

However, I’m still struggling with:
 

1. The connection to Spotify on my Sonos setup (very inconsistent access and frequent audio dropouts), whereas access to my own large music library is extremely fast and flawless.
2. Slow or no display of Netflix and other services on my smart TV (Samsung).
    

Since Sonos works flawlessly with my own music, I can’t help but think something is wrong with the music and TV streaming from the internet via the Sonos mesh and Deco mesh.
 

Any ideas?
 

Of course, I’ve updated and restarted all devices.