I have four Vortechs that I have setup in a master/slave/slave/slave relationship. Two of them are on one side of the back wall and the other two are on the other side of the back wall. The controllers are mounted under the pumps locations which are four feet apart. Recently I have noticed that when I disconnect power from all the units I also lose the communications with the two slaves that are on the opposite end where the master is located. Is four feet too far for the wireless communication to be reliable? Does it matter what order I restore power to the units? I never have an issue with the slave that is mounted directly under the master.