Quote from @Nadine Wallace: You can do simplisafe with/without Wi-Fi, but you will need cellular service.

I have found 5g cellular modems to be spotty.

They do make a few cameras that work off of the cellular network as opposed to a wifi - I think they are fairly affordable as well.

We want a camera system that:1) Connects to internet for remote monitoring via an office computer (not just a mobile device)2) Has motion-sensor alerts3) Records to the cloud, so a thief can't disable/steal the camera to hide their identityWe plan to remove these cameras once a property is rented and reinstall at the next vacant rental.Wi-Fi connection to internet is possible, but we'd also like to look into cellular connections to internet.What suggestions do you have please?

Here is my current set up:1) ShowMojo for managing the self showing listings (It has some self showing anti-fraud services, syncs with smart lockbox to issues codes, etc etc)2) CodeBox Jr smart lockbox where I have the keys3) ReoLink Go Plus Cellular Camera with a $5 per month T mobile data only sim card.

During renovation: getting a wireless solar cellular camera with motion sensors, night vision and lighting or post Renovation a Ring and or simplisafe system while your project is on the market.

And if you are subscribed to a monitoring plan that includes cellular backup, your Base Station will still communicate with our cellular connection back-up."

I tried a lot of the free resources and most of the numbers are not working.Look up “National Cellular Directory”, they might have what you seek. 

After closing sold a cellular tower lease that generated $790,000 in cash reducing our acquisition price down to ~$56.00 per SF What made you interested in investing in this type of deal?

In the event that you do have a true squatter its a fairly standard eviction process which is unfortunate but does happen in this business.On a preventative note if you have a vacant unit you can put in a security system that uses cellular and you will get notification if anyone comes in.