Connecting multiple speakers with wire

Wouldn’t it be simpler to correct your WIFI issues that it would be to run audio cable through your home? 
How old is your home?

What are the interior walls made of?

What router/ network do you currently use?

What have you tried to fix your connection issues?

You’ll need the Sonos combo adaptor. If you want to hard-wire all 3 you’ll need three of them - an adaptor for each speaker.  https://www.sonos.com/en-us/shop/sonos-combo-adapter-black

Then plug your phone into any of the adaptors via the line-in using an appropriate cable. Run Ethernet cables back to your router from each speaker. 
 

But, as ​@Pools-3015 says, fixing your wifi may be easier. Mesh WiFi, perhaps? It seems odd to buy wireless speakers and then wire them together. 

Reading argumentation like this, the idea of wiring the “wireless” speakers seams not weird but absolutely smart move.
Of course if your plan is to have a good party time, not to ruin it. 😀

Why not just Bluetooth to one speaker and group the others in. However your phone needs to remain close to the  original speaker.

Poor wifi was an issue stated in the original post. 

Oops 😂

👍😜

Also, if the wireless speakers are below the crowd, perhaps on the floor or tables, you are burying the speakers in water bags. Bluetooth is no better than WiFi in this respect. All of this may be inconvenient or frustrate aesthetic preferences, but it’s just part of the laws of physics that cannot be repealed.

thanks for the advice! Would hard wiring all the speakers through Ethernet prevent the music from dropping out? 

Because you won’t be transporting sound via WiFi, that is more susceptible to interference.