@chestermanBR 

If you connect your computer to the 840 does the computer indicate there is an internet connection? Or if you take the cable from the 840 to verify internet on that?

Have you tried connecting to the 840 with a visible SSID??

Hi @Tony 

Yes. I tried both configuration (hidden and visible SSID), and also with the SSID with the same name or a different name from the main AP. Also, connecting through the ethernet cable made no difference.

And yes, connecting directly to 840 I have internet connectivy (both with cable and wifi).

I have many devices (cellphones, notebooks, desktops, IoT, remote APs...) working fine in this network connecting to the 840, via wifi and also via ethernet cable. 

@chestermanBR 

What you can possibly do is to configure the TL-WA855RE to be your DHCP server.

Here is how you would log into the extender to configure it: link

You would then configure the extender below:

If you are unsure how to go about configuring the extender I would recommend reaching out to your local support team.

@Tony 

Hi Tony. Tks again for your time and effort.

I'm a little reticent in putting my DHCP server on one little extender on the edge of the network, when I have perfectly working DHCP server on the main router. Anyway, i'll go to my ranch this weekend (where the problem is happening) and give it a try, at least for testing purposes.

I read in a obscure blog or forum somewhere (i not finding the link right now) that, for some reason unknown to me, this device ONLY operate in the 192.168.x.x network. Have you heard of this? Note that when I'm saying "connects but no internet" is not just my windows network indicator that says that there is no internet, is picture in the status screen in the extender.

When I setup the DHCP server on the extender or set to off and configure a manual IP to my pc, I can ping the extender, but I cannot ping the rest of the network. Also, when i set the extender to obtain an IP automatically, it does not obtains, and go back to the default (192.168.0.254). 

Also, even when I configure the extender with a manual IP in the range of the the main network, and try to enable DHCP. when i get the IP, i don't get the route to reach the internet through the configured gateway, and I can't even ping the gateway.