@Solla-topee thanks, as I said, I did that... But after changing the operation mode as instructed, it auto reboot. After this reboot the problems begin.

Please read my initial ticket...

Thanks,

Ran

Solve it! 

here is what you need to do in order to make the router operate as wi-fi router

After trial & error that what i should have done in the first place

1.only if your modem lan ip is 192.168.1.1  Turn off completely the modem or disconnect it from the router (wifi is not enough, as the lan ip conflicts with each other)

2. http://tplinkmodem.net/ -> connection -> isp -> choose Other -> Dynamic IP (Thanks! but why is it not stated anywhere?)

3. Change operation-mode to wi-fi router. (in advance)

 only if your modem lan ip is 192.168.1.1 

           4. change the router lan address (so it will not conflict)  (after a hard reset I needed to do it again of course).

           5. turn on the modem

           6. change again the internet to dynamic IP (it is necessary for the router to detect all the network data)

7. That's it! Yeah. thanks.