@vDex Thanks for screenshots. From your initial post I assumed you only have two Deco: Main and one Satellite. Your screenshot shows four Deco in total. That is important information for...

@arnonm Before discussing what might go wrong with Main Deco in AP mode, I want to say that it is usually OK to run Deco mesh in Router mode, even if it is connected to ISP router. There are very few...

@devilson911 Start with the following TP-Link document: General questions about Ethernet Backhaul feature on your Deco

@vDex If you can tell what speeds you are getting with device connected to Main Deco P9 and what speeds - when connected to Satellite Deco P9, that will help to figure what does "very big loss" mean...

@arnonm IP address 192.168.68.1 means Main Deco still runs as a Router, not as an Access Point. In Access Point mode, Main Deco still must be wired to your router with Ethernet cable. Have you,...

@Kossie See this forum topic: https://community.tp-link.com/en/home/forum/topic/599920