Home Networking Setup

I am having a hard time figuring out the best way to connect this with as little interferance as possible.  I have a two-story house, about 2600sqft. I have over 40 wifi devices that are connected  (smart home with over that many devices... if  look at my  Device Manager on what's connected to 2.4/5ghz, there's that many, plus more depending!).

Main factor:

I want  my multimedia PC to transfer files back and forth as much as possible with as little issue as possible to the NAS, which makes WiFi a no go. My NAS is also a Plex server to share video content in which I create (4K) to family and friends and professionally so I want to avoid buffering where ever possible while streaming.  My family also uses Plex via their handle devices such as tablets, phones, roku, etc... I have other TVs and downstairs in the living room which guests comes and I share my videos there as well, not to mention streaming 4k Netflix shows. Additionally, I do have a ethernet CAT 5e line running from where my modem/router is  (upstairs) to the living room downstairs, where I'm thinking the Mesh should be for downstair wifi users... I have one additional multimedia PC downstairs for when I have a working sessions, which is not as important in file transfer, but would like to avoid connecting using it via wifi if possible or have solid connection without interference.

Permanent Network Location:

The  Arris SURFboard SB8200 (modem) is located on the second floor, which is connected to the XR700 X6S (Router) via wan. The multimedia PC is upstairs near the modem/router. There is also a gaming PC in the same room which cannot be relocated.

10 gbe Ports:

Multimedia PC: one 10gbe port

QNAP  TVS-671 (NAS) has four 10gbe ports

GS810EMS  SX10 (Switch)  has two 10gbe ports

The  router has one 10gbe port

Thought:

Here's what I'm thinking- upstairs near modem/router, connect CAT 7 from multimedia PC to NAS 10gbe port. Connect CAT7 from NAS to the Switch's 10gbe port. Connect the CAT 5e from the EX8000 (Mesh)  downstairs living room to the switch's 1GB/Lan port upstairs to enable wifi throughout the house. Connect CAT7 from the switch  to the router's 10Gbe port.  Let the router handle DCHP server.

Note: Currently the mesh is not set up, and I'm getting okay signal but with wifi drops here and there though from my router... Not sure if I should have only the Mesh handle all wifi and turn off the router wifi, or if it's best to have both on.

Does this seem right? Or is there a better configuration/setup? DCHP server from router okay or putting too much stress on it?   Or did I totally waste all my money and should have gotten a better, more efficient system for my home networking solution? I totally appreciate your time, help, and recommendations!