@Gogo_alb Deco E4 hardware specifications, Ethernet: 2× 10/100 Mbps Ports Deco E4 can't do faster than 100Mbps on wired connection.

@GergoPalfi Start with the following document, it discusses how Deco mesh can be wired: General questions about Ethernet Backhaul feature on your Deco What you want will work if you run Deco mesh in...

@TiagoRocha Start with this document: Troubleshooting: Slow Internet Speed with Deco Devices

@Bizzyh87 Can you clarify what do you mean by "I cannot connect the NAS to the P9's and the PC?" To start with, on your network diagram NAS is connected to the Router, which is the right thing to do...

@AnFe Either way should work, but it may be easier to do initial Deco mesh configuration with Main Deco connected by Ethernet cable to the router.

@padraig TP-Link does not seem to offer power supplies. You can buy third-party power supply adapter with the following specs: 1. Output: 12V 1.2A. Note that amperage can be higher, i.e., 1.5A, 1.8A...