@TP-Link Hi, the first picture is copying files on the computer from NAS in the Local LAN.

The second picture is copying files from an FTP (not mine) via the internet. Its perhaps a red herring. The point is that I think I should be getting speeds much greater than 12Mb/s. I'm not sure how to troubleshoot.

 

Sniipe wrote

The point is that I think I should be getting speeds much greater than 12Mb/s. I'm not sure how to troubleshoot.

@Sniipe 

 

What is the speed of your Internet connection?

 

Now, for troubleshooting of file transfers between NAS and Windows 10 desktop PC. It appears as if somewhere you are getting 100Mbit link instead of gigabit, or may be even half-duplex 100Mbit, so this will be the target of investigation. 

 

Also, once I've seen misconfigured (or hacked) system that did local files transfer through the Internet. This is quite rare, but worth checking and dismissing.

 

You run your Deco mesh in router mode. It makes testing easier, because we can use Main Deco as a router, move it around, without messing with IP addresses allocations for your home network.

 

So, three tests I'll suggest:

 

1. Check on NAS and on desktop PC that they have negotiated gigabit link to the Belkin switch.

 

It is basics, but sometimes people forget about it.

 

2. Confirm that the file transfer between NAS and PC is, indeed, local.

 

Disconnect the Ethernet cable between Main Deco and ISP modem. You will make your home network separated from the Internet. Main Deco LED will go Red, but it'll continue working as a router.

 

 

 

Don't do any other changes on your home network. Try to transfer files from NAS to desktop PC. If transfer fails, that could hint at this unusual issue with local data traffic traversing over the Internet.

 

 

3. Try copying files without Belkin switch

 

If you can move Satellite Deco to where Belkin switch is, connect NAS and desktop PC cables to its Ethernet ports and use its wireless backhaul to Main Deco, try copying files in that configuration.