@Xavier79 

Yes, you can. I have Yamaha wx10 speaker connected by wire to slave deco unit in second room.

But speed on slave deco will be degraded to about half of master unit Wi-Fi speed, even with perfect signal strength.

I can get about 460mbps on master unit Wi-Fi, but on slave only 220mbps with 100% signal strength between deco units. I tested the connection with both units standing next to each other.

So ethernet port on slave deco will work at this speed maximum. If the signal strength drops, the speed decreases further.

@Martimezcb 

Do you need to change any settings or configure IP addresses on your Yamaha speaker? Or slave deco?

Look forward to hearing from you.

Thank you. 

@Xavier79 

What do you have to configure to get your NAS working on the slave deco?

Look forward to hearing from you.

Thank you.

@Solutions 

I didn't have to change anything. All connected DECOs operate in the same subnet, their IP addresses cannot be changed separately. The entire DECO network can be treated as a single router (Deco in router mode) or switch (Deco in AP mode). You can connect devices to it via Wi-Fi or any Ethernet port, and these ports are now scattered across the slave units, regardless of how they are connected to each other (wifi / cable)