Hello Sam,
Thank you for posting your query on Microsoft community.
As per your description, I understand that you are facing issues with default gateway on your Windows 7 computer.
I would suggest you to follow the suggestions given by Sharief K on April 5, 2013 and see if it helps.
Please do reply and let us know if you need further assistance with Windows, we’ll be glad to assist you.
Thanks and Regards
Sarandeep S - Microsoft Support.