TP-Link Deco M4 loses every day the connection with the KPN router

Hello

We changed from Ziggo to KPN Fiberglass 10 days ago. The offer from KPN was too good to decline. The sales guy said that WIFI extenders are not necessary as the Fiberglass would cover the entire apartment. Of course complete nonsense. The internet itself is good when you are close to the WIFI-router. However in the far away rooms there is zero reception. So I am using the exact same mesh WIFI-extenders that Ziggo gave me (Deco TP-Link M4). WIth Ziggo I never once in 5 years had an issue with them (not once did I have to reset them, not once did they lose connection etc.)

Now that I am with KPN literally every morning the main DECO one has lost the connection to the KPN-router (they are connected by cable). Therefore every single morning I have to unplug the main DECO and plug it back in. That usually resolves the issue. 

So it cannot be the DECO’s as they literally worked 100% till we moved to KPN. Plus, they work just fine after unplugging/plugging. So it must be the KPN-router that just disconnects the internet for a few seconds and therefore the DECO looses connection. 

It is so annoying that I am honestly considering in going back to ZIGGO. 

I googled the issue and found quite a few posts about this, but no actual solution.