Neighbors devices somehow connected to my moca?

I started service this week at my new apartment and as soon as my router was turned on I saw there were 5 devices connected to my wifi, but I only own two. All of the other devices say they’re either wired to my router or connected via moca; both of which shouldn't be possible as I don’t share my wifi or apartment.

I called customer service and they said they couldn’t see anything on their end and that no one should be connected to my account, but I can’t remove the devices from my app meaning they’re still actively connected to my network. I have paused every device to try to get some speed back and it doesn’t help. I changed my password and wifi name and the devices immediately reconnected, but I had to manually reconnect my own. I tried making my wifi undiscoverable and the other devices still connect automatically, even after another password change, and I use incredibly strong passwords. 

At this point I don’t know what to do. My app says the speeds are amazing but I can’t load any webpages on my laptop besides outlook. The app says I can’t disconnect/forget a device until it’s disconnected from my network, but I can’t remove them from the connection on my end. Customer service said that the router I have from xfinity should already have a moca protecting my devices from roaming out and protecting my wifi from devices roaming in, but the mystery devices say they’re connected to the moca, and my laptop will randomly get paused even though I’m not doing it from my app. If the moca was working properly I don’t think I would be having these issues.

I’m thinking I need to install my own moca adapter before the router to keep my wifi and my devices in my apartment instead of wired through the whole building. Has anyone experienced this as well and what did you do to try to fix it?