Thanks for the observation. I tried reverting to both 12.3.2280 and 17.2.2288 on the WinXP host but still didn’t see Wi-Fi devices with either version. Maybe its an adapter setting. Earlier, with the 17.3.2290 version showing Wi-Fi clients on the WinXP host, I tried moving its adapter to the Win7 host, but that did not result in any change on Win 7. When I moved that adapter back to WinXP, that host no longer displayed the Wi-Fi clients. So at this point I think I’ll just go with 17.3.2290+91 everywhere and see if the adapter settings are consistent across hosts. My router is set to block anything but known MAC addresses, so I’m not too worried about intruding neighbors. Maybe Avast can investigate the feature for possible issues and some future update will magically find those stealthy Wi-Fi clients.