I have a new 21.5 iMac running 10.11.16 El Capitan. The computer keeps losing our wireless network connection and does not automatically rejoin it. This is pretty frustrating for a number of reasons. 1) We previously had a 27" 2010 iMac that was doing the same thing and we finally decided to replace it with this new one. So $2g's later and I have the same problem albeit on a much faster computer. 2) This computer serves as my music hub and also as our AirPrint terminal for our iPads and iPhones. So when the connection goes down we lose the printing and music until I go and manually reconnect to our network. 3) The message that is on screen when it drops is that it can't find our wireless network. It presents a list of other possible networks to join which is quite lengthy (must pick up every home in our neighborhood) but our own network IS always on the list of networks. I click our network and it joins. No other computer in our house has this problem and I am at a loss as to why it only happens with this computer. By the way, this computer is located less than 15' from our wireless hub so I don't think it is a connection issue. The computer indicates that it is connected on 802.11ac and transfers speeds around 700Mbps.