to ask how I stop my neighbour messing with my wireless speaker?

[MakeMisogynyAHateCrime]

My neighbour is a dick, a grade A dick. He has taken to now somehow talking to my wireless speaker (a KS Miami cheapy thing).
He just said
“My name dog, my name back door, my name silly cow”.

What I’m playing isn’t loud. I’m playing the sound from my broken iPad which plays at about half the normal rate (I prop the iPad on my drawers but can’t hear it at all and then play the speaker next to me at a low volume - about half iPhone max volume and never after 20:30) it in my bedroom.

How do I prevent him from using it? The device just seems to be a case of turning it on and then syncing your device with no codes or anything.
Our internet is secure but this is really bugging me.

[Hebenon]

Get a better speaker with better security. Something like a Google Home or Alexa won't let just anyone control it. They have to be connected to your wifi or able to actually speak to it.