For the AIO you can try this
Find the button on the side of the AIO unit and hold it in for a couple of seconds and let go and you should hear some clanking, after a few seconds press the button again and wait up to 5 minutes for it to cycle back up and see if its able to connect on the app.
How are you wired, LAN or Wireless? It COULD be the infamous comms issue that can crop up and there is a solution that will have to be applied when its online but only ask if you have constant issues.
If you are running via a network switch you may have to just power cycle that, my old Netgear switch was faultless but my new 8 port one every now and then just shuts down traffic which is weird.
If the soft reset does nothing for you you could press the button on the side of the AIO and when its done with the clanking then flip the breaker next to it in the cover down and then flip the AIO breaker in the gateway til the lights go off then reverse the procedure.
You will need to again give it up to 5 minutes to properly all kick back on again, if it still isn't connecting and you have an IHD make sure the battery is providing power to the home (the grid draw will disappear) if it isn't you may need to just press the button on the side again.