No, this is mac from router interface. This same wired and wireless interface (bridge). Sometimes repeater mode has problem with another devices not Tp-link. To jest mac interfejsu sieciowego, taki...

Channel in status after refresh is this same (11) all time? When you make wireless connection give me information about addresses on wireless card. Kanał w statusie jest cały czas ten sam (11)? Kiedy...

Have you entered DNS in main router? My proposition try default configuration on WDR4300 and after that make new configuration.

But you have some problem with connection in this mode (we have to localize issue). Oryginal IP on this device is 192.168.0.1 and you have to write this addrressation in your computer For example...

You have to write addresses in your computer network card because probably DHCP on router is disabled (switch off). Musisz wpisać jakiś adres do karty sieciowej (z puli routera) aby móc się z nim...

Please complete DNS in main router, for example 8.8.8.8 and 8.8.4.4 click SAVE and Reboot router. After that try to connect.