hi,

maybe you can help me.

I have:
MyLocal LAN with DHCP Router (IP 192.168.0.1) <-> connected from LAN to WAN of TP LINK 841ND
It has the ip 192.168.1.1 - DHCP default on, wifi  SSID + WPA2 set, Access Point WDS --> nothing else changed

The SECOND TP LINK 841ND (client) -> hast the ip 192.168.1.2 -> DHCP off, scan for wifi, logged in into wifi from sender OK. checked LAN (green one) and not WAN. Saved & Applied. Then admin panel site reloads and the checkbox shown has wan checked is this correct?

Problem: I have no internet connection on both devices, the cable is fine (pluged on wan port) AND do i have all configured well done? or is something missing

Little confused, should be an easy thing.
By the way, all router have the same firmware, are resetted and clean.

If you are going to do WDS, you need to do it on both ends. I haven't had much success with WDS since the early days of the WRT54G, so it may not work.

If you are just looking to client the 2nd router off the first, then put the first router in AP mode. But be aware this will only work for IPv4. IPv6 doesn't work in "client mode" (hint: you have to setup routed WLANs like HomeNet to get IPv6 working across wireless)

First find out why the first one has no Internet.  Since the main router is not 192.168.1.x, simply using default settings where WAN pulls a DHCP address should work.

AP (WDS) -- STA (WDS) works really well between two ath9k devices such as these.