I have 5 Deco M5's, in router mode, in a 2-story home. The main and one other on the first floor. Three strategically placed on the second floor. Since the upgrade WiFi has been completely unstable. Devices are constantly going on and off line and/or not coming back online, at all. Signal strength is poor even when close to one of the M5's. But the app continues to say everything is perfect. WiFi Optimizer also says everything is perfect. This is not a new installation. This has been in place for over 3 years without any issues. @TP-Link please release an update to correct this asap. Or provide a rollback option within the app.