I, too, have been struggling with getting the Z-Wave signal into the garage where we have a door lock and open/close sensor. The open/close sensor works perfectly, but the Z-Wave lock is DOA. I sent a support request into SmartThings Help Desk, and they have not responded as to their supported means for relaying a Z-Wave message to a Z-Wave lock. I briefly tried a Aeon Labs Aeotec Z-Wave Smart Switch 6, Gen5 and it only repeated the signal about 5 feet when the device was placed about 10’ from the hub (which is the furthest it could be located from the V2 hub). What a disappointment.
I have since order a dedicated Z-wave repeater (Aeon Labs Aeotec Z-Wave Range Extender/Repeater (DSD37-ZWUS)) that I will let you know if it performs any better. I am not getting my expectations up.
You would think that the SmartThings Range Guide/TIP/FAQ would help us in this regard rather than explain in great detail what most of us already know about signal strength loss and walls, glass, brick, stone, sun spots, frequency bands, etc… Just name the repeater devices that are supported in the different device connectivity situations and I will gladly purchase… 