its about your computers ability to process data, data goes through the CPU and ram (which I doubt it the issues but NM)
you are testing your Iphone over wifi, this is a different technology to Ethernet with different overheads etc. you cant really compare your testes to those you don't on the computer.
now try answering what speed is your Ethernet computer connected to your router at? what network card does it have in it? what model of laptop is it?
those questions will likely provide more answers than anything that has been said before in this thread.