Question about range

So I am trying to install a Z Wave switch inside of my low voltage outdoor lighting box. I have another Z Wave switch pretty much on the inside wall that works just fine but when I install another one outside, it isn't receiving the signal at all, even with the cover of the box open. I don't understand why it's not working as it's my understanding that each plug-in switch works as an extender so it should be working. Any ideas?

These are the switches that I'm using: HAOZEE Z Wave Plus Mini Smart Power Plug

These are also sold as Neo Coolcam z-wave plus mini plug:

They have very poor z-wave radios. I was just complaining to @bcopeland about how bad they were a few days ago.

Which ones would you recommend?

I'll let someone else answer this. I just removed 6 of the Neo Coolcam z-wave plug-in outlets from my z-wave network.