AlexR85,

If you are running your Sonos system on SonosNet, then you ‘likely’ do not need to add your router WiFi credentials to your setup, in fact I would suggest you remove the credentials, as that will ensure your products do not ‘hop’ between SonosNet and the the WiFi signal.

There are a few things you could perhaps try with your setup…

1. You could enter/keep your WiFi credentials installed and uncable all your devices and try running them entirely on your WiFi 2.4Ghz band - If doing that, I would suggest trying them on a ‘fixed’ ‘non-overlapping’ channel 1, 6 or 11 with a channel-width set to 20MHz. Try each channel for 30mins+ to see which works best for your home environment.
2. As an alternative to the above, you could leave one Sonos device (at least) wired to your main router and run all on SonosNet instead, which I personally prefer. If you choose this option, then also see the following additional information…

The following link explains the difference between the WiFi/SonosNet connections and how each setup works, so perhaps have a quick read of that:

https://support.sonos.com/s/article/3235

If opting for SonosNet (wired) mode, I would suggest doing these few things:

• Ensure (as in step 1 above) you set the routers 2.4Ghz WiFi to a fixed ‘non-overlapping’ channel 1, 6 or 11 and choose a 20MHz channel-width.
• Set the SonosNet channel in the Sonos App “Settings/System/Network” so it is at least 5 channels away from your chosen/preferred router channel.
• Remove the WiFi credentials from the "Network/Wireless Setup” in the App, as those are not needed, as mentioned earlier.
• Ensure all Sonos products, particularly the wired ones, are at least 3 to 4 feet away from other Wireless devices including the router and other access points.
• This next suggestion is optional, but is often worthwhile... Consider adding the Sonos IP addresses to the local routers DHCP reservation table, as that too will improve stability, particularly during updates and reboots of the local network.

Hopefully those few suggestion will assist to prevent audio and speaker dropouts… I also recommend checking out these two ‘hopefully’ helpful links too:

1. WiFi Interference
2. Wireless Interference Video: Wireless Interference and Sonos

That last suggestion on reserving IP addresses is where I’d start.

I had a horribly unstable system and spent many hours fussing with it. Set the IP addresses, powered down all the Sonos, rebooted router and controller, powered up the Sonos (wired first) and my issues went away.

I prefer the SonosNet (wired Ethernet to one or more Sonos) too as it lets me use the full capabilities of my WiFi system without having to support the legacy settings Sonos requires.