I recently got a firmware update which I let the Deco app install. I have 5 Deco M5s, but one was unplugged so it didn't upgrade.

After the whole Deco system restarted, my wifi was (and is) working normally. The fifth Deco is plugged in again and shows Green.

When I first started the Deco app on my iPhone with iOS 15, it showed a little Deco with a red circle with an exclamation point  in it. Then it went to a screen that said "We couldn't find Deco". Again, there is a picture of Deco with the #1 in a red circle. The test below reads:

"Something went wrong with the Cloud service. Please try again."

Hitting "Try again" gets me a turning circle over the normal Deco app home screen, but then it is replaced with the "We couldn't find Deco" screen. All the while, my laptop and iPhone are connecting to the Deco wifi normally. I have included a screenshot. Sorry I don't know how to make it smaller.

Early this evening, the Deco app started working normally. There was no red circle with ! on a Deco. I could see the list of current and offline clients, etc. That was short lived. Within a few minutes, all I could see was that "something went wrong with the Cloud service" screen. I can't see anything more.

If I login to the main Deco using Firefox on my laptop, everything looks normal. It shows all 5 Deco's. Each one shows some CPU and memory usage, varying slightly over time.

Four of the Deco's show firmware 1.5.7 Build 20210819. The Deco that was unplugged when I did the last upgrade shows firmware 1.5.3 Build 20210203.   I cannot see any way to upgrade that one Deco. If I click on Online upgrade firmware, I just get a turning circle forever. Well, for at least 15 minutes.

My two main questions are:

1. How to get the Deco app working normally?

2. How to do a firmware upgrade on the one Deco that didn't get upgraded before?

Thank you for any advice.