@LSoft 

Hi,

If you have set the DHCP server of the Archer C6 to OFF, then how are your client devices getting their IP addresses assigned?

Is there another device with a DHCP server inside your network?

  @woozle Yeah, this is something what was also not clear to me. I asked my internet provider who made initial setup of my router, so far I am waiting for response.

And I have no other DHCP servers in my network, only that C6 router. But could be DHCP is driven by provider's server managing my router. Let's see.

  @LSoft 

You can find out by yourself.

Go to the "Operation Mode" menu and check whether your C6 is set to "Router" or "Access Point".

In case it is set to "Access Point", then yes, your Internet provider is managing the IP addresses assigned to your devices.

What sort of broadband connection are you using? Like DSL, cable or fiber?

  @woozle Thanks for your reply Woozle!

I checked the "Operation Mode" menu and my C6 is set to "Access Point". And I am connected to my internet provider wirelessly.

Do you please think I could change the "Operation Mode" to "Router" myself or shall I firstly discuss such change with my internet provider?

  @LSoft 

Whether you could change it depends on the whole setup.

How is the Archer C6 connected to your internet provider wirelessly?

Is there a network cable plugged into the blue WAN port of the Archer C6 or not?

I am asking because normally TP-Link's routers have no option to connect to the another wireless network in Access Point mode.

  @woozle There is a wifi antenna on my house and it's connected to router's WAN port by ethernet cable.

  @LSoft 

Ok. Is it something that looks like this https://www.tp-link.com/en/business-networking/pharos-cpe/cpe510/ or this https://www.tp-link.com/en/business-networking/omada-wifi-outdoor/eap225-outdoor/ ?

Then I guess it should be possible to connect the Archer C6 in Router mode.

The best way to find out would be if you had another (old) router lying around that you could use to test this with.

Or connect a computer with Ethernet port directly to cable coming from the "antenna".

Anyway, whatever you do make sure you first perform a "Backup" of the Archer C6's current settings via the "System Tools" -> "Backup & Restore" menu. If you have a working backup, then you can always revert the Archer C6 to its current state by restoring the backup file via "Restore".