Base to sensor distance

Thanks for reaching out about this. Since the Smart Lock does have to be in more constant contact with the Base Station, with all that info needing to be encrypted as well, it unfortunately doesn't have the same super-high range as the sensors, and would be more akin to the Keypad. The brick wall would definitely be a big detriment, and so would any other dense physical obstructions - like say if your garage siding or the door was made of metal.

You do mention that this is more of a recent issue. Could you have installed a new wireless device recently that could be interfering as well? We're probably looking for lower-frequency devices, like garage door openers, wireless weather stations, etc.
Also you said that we had already replaced the unit. How long has that one been in place? I was thinking the battery might be running lower, but you shouldn't be seeing decreased performance for at least 6-8 months.

@worthing​ The sensor that is having problems in my system is a lock that’s on the door to a detached garage. From where the base station is currently sitting, the lock is 51’ away (measured). The only obstructions are the brick exterior of the house and the garage door that the lock is attached to. Additionally, the base station sits within 2’ of a window that has line of site to the lock. 

Would you think my circumstance would be an environment where I shouldn’t expect the lock to work? To make matters more curious, the garage also houses an entry sensor, a motion sensor, and a smoke detector, all of which are working fine and all are even further away from the base station than the lock. 

I can find plenty of data for how building materials blocks Wi-Fi:

https://eyenetworks.no/en/wifi-signal-loss-by-material/

But I'm not sure how much of that applies to the RF frequency that SimpliSafe uses for their stuff.

I would guess that, generally speaking, the glass isn't much of an issues (unless it has coating designed to stop RF which is unlikely?) but the brick and the metal garage door (if metal clad) are likely culprits.

That said, if you have other devices that are working fine in the same space (and you do - the entry sensor, the motion sensor, etc.) it's likely either the radio in the lock itself or it's placement on/behind a metal clad door (if it's a metal clad door which if it's exterior would likely be?) or a bit of both are the issue.

If it wasn't already installed (and I assume it is?) I'd say move it away from the door, middle of the garage, and see if that works. I can't say that it will, but it's a solid trouble shooting step. I will also say that connectivity issues with the lock seem to be reported not infrequently? I know I've had some issues and my base station is 20 feet (as the crow flies) from my lock which is on a door between the attached garage and mud room/laundry room. It's almost line of site except for the edge of a drywall wall.