My Internet Speed is 250MBS. If I connect an Ethernet cable from my modem then the speed is coming to 220mbs but if I connect that cable to Archer C20 router then the wifi speed is coming 80mbs. C20 ad says that wifi speed can reach maximum to 433 mbs.

I have called tp link twice but they saying its maximum wifi speed is 100 mbs only. i cannot get speed more than 100 mbs whereas my internet bundel is 250 mbs. Can someone suggest if the speed can be increased or not?