Two Computers - Only One Will Connect Through Wireless

I have a home wireless network and my service provider is Suddenlink. I use a DLink modem and have two Tosiba laptops. All of this has been working fine until this morning when one of the laptops won't connect to the internet. when I run the trouble shooting guides on it I get messages that the problem is that the modem won't connect to the internet. However, the other laptop (this one) is working fine. when I look at the network map i see both computers and a green line to the modem. on this computer, there is also a green line from modem to internet. the other computer shows a res x on the modem to internet line. this is a sudden change i have restarted the computer the modem and the router. I can also conenect this computer to the internet via a mifi that I have but not the other laptop. there are no red x's on any of the hardware when I go to the "manage" computer.