Good connection to local network, unable to access Internet

Note: I have already posted this question in the ‘Networking’ topic area ( see https://www.experts-exchange.com/questions/21823204/Good-connection-to-local-network-unable-to-access-Internet.html ) That posting is where the points (500) are assigned. I am posting the question in the ‘Broadband’ topic area, since this question may be more appropriately addressed here.

Q_21823204 text:
Hello,
I am having a problem connecting to the Internet with a laptop that I have attached to a working network at a friend’s house.
The working network is comprised of a Desktop and a laptop that are connected to a LinkSys wireless router, which in turn is connected to a broadband modem. This is a residential Comcast account. The desktop is directly connected to the router. The laptop uses a wireless connection. The wireless router is not encrypted, but is using MAC address filtering. This all works swimmingly.
So now I take my Sony Vaio laptop, which uses a wireless connection at home, and connect it to the LinkSys router wirelessly. After adding the MAC address for the Sony to the list on the router, it connects to the router with no difficulty. My problem is that I cannot get out onto the Internet. I am able to connect to and access the drives on the desktop PC, so I know the internal networking is OK. The ‘ipconfig /all’ looks OK. I am not able to ping a site that I know allows pings. Just to get this up and running I have disabled the firewall (although the connection to the desktop works fine with the firewall activated).
I am not sure what to look at next. Any suggestions would be greatly appreciated. I am going to bed right now (02:26 AM EST), but I will be picking this back up first thing later this morning.
Thank you,
Shambalad