The GoControl device that you have is classic Zwave, right?
Any Zwave plus device (including the iris plug or the DragonTech) has a range about 50% farther than classic zwave.
We just had a community member last week who was having trouble getting zwave signal out to a shed in his yard and he added a DragonTech pocket socket inside the shed and was able to connect to the other Zwave devices in the shed after that.