Slow internent Speed

[Luismm2311]

I just bought a new AC750 Wireless Dual Band Router, Archer C20, but after I set it up, the speed that gives me on both WI-FI and on ethernet cable is really low. I set it up flowing step by step the instructions to configure it in router mode but it gives me a maximum speed of 8Mbps while if I connect my pc directly to the same cable with which I connect the router to the modem, it gives me a minimum speed of 60Mbps. 
I already try to restart both the router and the modem, try to restore the router and start over and even try to update the router's firmware with the file I downloaded from "this page" but nothing. 
I don't know what to do anymore, I need help.

Router specs:
Brand: TP-Link
Model: Archer C20
Hardware Version: V5
Firmware version: 0.9.1 4.16 v0001.0 Build 190103 Rel.45825n (4553)

 

Thanks in advance.

[thedangerine]

What speeds do you currently pay your ISP for

[Luismm2311]

8 minutes ago, thedangerine said:

What speeds do you currently pay your ISP for

I pay for 60MB/s

[jj9987]

What are you using for speedtesting? If speedtest.net, are you using the same server each time?

 

And to be clear, a quite popular thing is to get units confused - Are we talking MB/s (megabytes per second) or Mb/s aka Mbps (megabits per second) here? That's an 8 times difference.

[Luismm2311]

1 minute ago, jj9987 said:

What are you using for speedtesting? If speedtest.net, are you using the same server each time?

 

And to be clear, a quite popular thing is to get units confused - Are we talking MB/s (megabytes per second) or Mb/s aka Mbps (megabits per second) here? That's an 8 times difference.

1.- I do use speedtest.net

2.- No, I am not using the same server each time

3.- Sorry, I meant Mbps

[RageTester]

Router could be broken, try to use it in repeater mode, disable dhcp server in the router settings

[Luismm2311]

12 hours ago, RageTester said:

Router could be broken, try to use it in repeater mode, disable dhcp server in the router settings

same problem 

[RageTester]

Always gotta look for weak spot.. Cheap routers might use 100 Mbps Ethernet ports(ends up at max 11-12MB/s), that might explain everything...

Router can't reach advertised wifi speeds if it's getting internet via such slow ethernet port. 

[Luismm2311]

I am beginning to think that the router came out defective and I will return it.
You could recommend a good and affordable router.