getway problem

i have dell laptop vistro 1015
the problem is i can open the internet and ping the getway from my desktop pc and log in others computers but i cant open the internet from my laptob with the same cable but there’s no problem with the network i can log in others computers from laptop i try to connect my laptop on different modem speed touch and its working but at my home i cant i need ur help plz to solve the problem i dont know if it from my laptop or from the modem speed touch st585 but i think there’s no problem with my laptop and the modem because my desktop pc is working good
need ur help plz