Have an existing 3-device E4 network which has been fine for the past 3 years. Unfortunately on of the satellite devices failed. I have purchased a replacement but I cannot get it to install on the network. When connected it flashes blue but does not connect. I have reset the network and tried all of the online recommendations. The new unit appears to be OK but does nor install in any location, Please help or I will have to return the device for credit.