If the sync module is inside of a building that has metal and/or concrete, it will be problematic.
Concrete and metal kill wifi signals. It’s the same concept for your cell phone. Bad inside a building but step outside and all the sudden you get a good cell phone signal.
Most residential homes are wood and sheet rock.
Most commercial buildings are metal and concrete.
The wifi antennas in the Blink camera and sync module are weak/small. Keeps cost down. You’ll notice better higher priced cameras have an external antenna.