I started having the same problem a couple of weeks ago after turning off stand-by mode (it was the first time I’d ever used stand-by mode). The device has worked great for as long as I’ve had it. I read through this thread and saw the note about a possible fix a couple of nights ago. However, this morning I received the notification that my Rachio had been offline for 24 hours again. Apparently it went offline about 90 minutes after I had last power-cycled it to bring it back online from the previous day. Here’s a rundown of the incidents:
11/14 4:10 PM - Standby Mode OFF
11/21 3:00 PM - Controller Offline (first occurrence)
11/21 4:18 PM - Power Cycle (manually unplugged)
11/22 11:00 PM - Controller Offline
11/24 1:56 PM - Power Cycle
11/24 3:46 PM - Power Cycle
11/24 4:21 PM - Power Cycle
11/25 11:09 PM - Power Cycle
11/26 12:57 AM - Power Cycle
11/27 2:00 AM - Controller Offline
11/27 6:34 AM - Power Cycle (manually unplugged)
11/28 8:00 AM - Controller Offline
I also ran the RouteThis test. My key is K4XG8QKG.
Hope that helps find a fix.