Region : Vietnam

Model : TL-WR740N

Hardware Version : V4

Firmware Version :

ISP :

I have 2 TP-link, both of them are TL-WR740N..
First, I connect Modern -> 1st TP link -> Computers. That is ok, I can connect to internet..
Second, I connect Modern _> 1st Tp link -> 2nd Tp link -> Computers (The cable between 1st and 2nd TP link is 1 meter). That is OK, I can connect to internet.
Third, I connect Modern _> 1st Tp link -> 2nd Tp link -> Computers (The cable between 1st and 2nd TP link is 20 meters). I cant connect to internet, at 2nd - TP link,
WAN light is not illuminated.
Please help me..