@Marvin_S 

> Did your ever try different LAN ports on the router for your computer?

I've tried a couple.

> Do you have other wired devices and can they connect the the modem router via Ethernet cable properly?

> If possible, if you connect your computer to the other network device via Ethernet cable, does the internet access work?

I've connected a laptop and it has the same problem. (it connects fine via Wifi)

> Did you check the wired adapter in your computer?

I've gone through every setting I can think of in the adapter.

If I do a complete reset of the router and run the config again the PC connects up. But over time it seems like the DHCP pool fills up for some reason and the server thinks its assigned all the addresses so then if the PC resets, or I power it down over night it won't connect and gives declined errors to the DHCP server and I have to reset it again.

  @Marvin_S 

The PC isn't dropping offered IPs, it sends declines because the address is marked as in use. When I reset the router (thus clearing the address pool) the PC picks up an IP address straight away which clearly indicated the issue isn't with the PC. This happens both on a PC and on a laptop. Different opperating systems and different hardware. And I've never had problems before on non-TPLink modems.

I've also never seen a DHCP server's pool fill up with not actually assigned IP address like this before. I think there's something odd about the TPLink DHCP server implimentation on these routers.