Really strange connectivity problem

My Orbi RK50 network (one router, two satellites) have worked flawlessly since I bought it last summer. Suddenly, two days ago, the network started to not work in a really strange way:

- It appeared that all WiFi units disconnected. 

- I could however connect to the router via WiFi.

- One unit connected via cable was still connected (that is a server with a DynDNS setup which was setup three months ago).

- Another unit connecte via cable was not connected.

- Sometimes during this time I can open the Orbi App on my iPhone and see a red dot nex to the router. I can never see the reason why that dot is there though.

Basically; Everything on the network is not reachable except for the hardwired server. And all of a sudden with absolutely no settings changed!?

A restart solves the problem, for a couple of hours. I have restared the router 6 times the last two days. 

Latest firmware (2.7.2.104), and as I said no alterations to the settings.

I know that the ISP have done some work in the neighbourhood the days before this happened. But how could that impact my WiFI but not the wired unit?

Please help me understand this, and also if there are any logs I could go through etc?

Edit: I am not sure, but it feels like the router interface pages are much slower than usual. 4-10 seconds to load a page? But it was a couple of months since I last was logged in, so it's maybe this slow normally...