@MartinL61 You can't, but there are workarounds. You can disable 2.4GHz for Main Network and enable Guest Network or IoT Network with 2.4GHz only and different SSID.

@ZappoZero Nodes that connect to each other with Ethernet cable do not count as extra hops in daisy chain, which means all three setups will provide equivalent WiFi coverage and speed for Room 4. For...

@toomanymatts It should work when powerline adapter in the closet is connected to the primary E4 node. It may or may not work if you connect powerline adapter directly to the router. These are tests...

@toomanymatts One more thing: you have two powerline adapters, one is in the bedroom. Where is second powerline adapter and what is it connected to? This part is not clear from your original post.

@toomanymatts 1. Can the Deco E4 actually use Ethernet backhaul via Powerline adapters, or is GPT simply wrong? Yes, it can. I tested that at my house, but with different brand of powerline adapters....

@absheikh If you use Synology NAS Media Server, try this: Go to Media Server > DMA Compatibility. Uncheck Restrict access to Media Server for newly detected UPnP/DLNA devices.