Aeotec nanomote connection problems

I intend to use the nanomote as a remote control to open nd close the garage door from within the car.
When I leave, the remote works well consistently, the close command gets executed within a second. When coming back home though (remote was away from the zwave network), it frequently does not get a signal back to the controller. Every now and then, it works fine though.
How exactly does zwave work in this scenario? How and when does the remote connect back into the network?

An additional thought: with the garage door open (when leaving) the signal may actually travel via the switch that controls the door. With the garage door closed, it may actually have to take a different route, via a zwave repeater that is mounted outside of the garage. Would that be a possible cause of the problem??