@Alexandre. That did the trick! thx!

@David-TP My Modem is the standard Ziggo Connectbox. First I tested with speedtest.net, but if I test via the deco it seems to be OK... What could cause the difference between the reported speed from...

My internet just had an upgrade from 300/30 to 350/35 Mbps. If I connect directly to the modem router I get 350, but from the deco m9 plus i get still max 300 (cabled) I already rebooted it, but it...

@T7H Tried all of that already, router in bridgemode, use as access point etc etc... nothing worked until I changed the cable --> 300Mbit!

I used to work fine with my old Ziggo modem, together with 3 Deco M9 devices set up as an access point. Now I had to change my old Ziggo Modem to a new Ziggo ConnectBox, so I thought it would be...