That looks like a KPN Experiabox, in which case I’m not surprised about your network being unstable. I recently bought a new house and was using the Experiabox until we moved in, and it was terrible. After we moved in I quickly replaced it with a proper router, no issues since.
There’s a very similar issue with Ziggo’s Connectbox, which also is pretty unstable.
I think it’s fair to say that Homey just doesn’t work well in combination with either one of these routers. It’s partly Homey’s fault too, because it apparently doesn’t recover when it loses its connection with the router.