It's not matter. You have to see model and hardware version of your router.

But the problem is why a direct cable from their router shows 20MB and TP Link gives me only 9PB Yes I know, but I'm trying catch the problem in your network. Last idea from my side if you have...

What kind of modem from ISP do you have? Can you see link speed on box diode?

Do you have link 100Mb/s or 1Gb/s from router (please see network card)? Can you check connection on another cables (patch cord)?

when i am using my TL-WR1043ND router in the middle to split the connection and wifi etc its giving me speed as 9mb only Is this wired connection between router and computer? i am getting pure 20mb...

Your main router?