@boardtc 

You can do the test to confirm the problem.

1. Connect your PC to the router directly to confirm whether your router can work normally.

2. Connect two PC to the switch directly then use two PC to ping each other, to confirm whether the switch is broken. May need to set static IP address for two PC. If they cannot ping each other, you should replace a new switch.

@Andone 

1. New router installed yesterday. Cat 6 wired Ethernet connection straight to laptop from back of router works 100% 

2. Cat 6 connection running from Eth1 port to port #1 on switch.

3. Cat 6 cable running from switch to laptop. Windows 10 network status: "Not connected. You are not connnected to any networks" I guess this is not enough to confirm it's dead, we need to make a loop with another machine from what you say. But, I'm not sure how to set static ip when there's no network adaptor as no connection is seen?

This is pretty new and has taken little traffic, with only 4 ports in use typically. Is it unusual to have failed? 

I want to confirm fauilure before sourcing replacement. Have I just got unlucky and would you replace like for like? That said on Amazon, where I bought it says "Lifetime Warranty"!!

Should any lights show uncder the numbers on the left hand side if I connect 2 ports on the switch with a patch? I never noticed before if they should show if ports are in use?

The key was that no lights were showing when LAN ports were connected. No other tests needed.

It's a lifetime warranty.

After about an hour with TP-link chat support they agreed to replace.