Hi,
I noticed that many users have such network issue, my suggestion here are:
1. Since this issue just happen in recent 3 weeks, please check if there is any update related to network adapter driver. Please try to roll back to an earlier version of network adapter driver to check your issue.
2. Change the power plan on Network adapter as the Max performance.
To help you better in further, I suggest you submit a new case on Surface forum as they will be more professional on your issue:
Contact Microsoft Support for Surface
http://www.microsoft.com/surface/en-sg/support/contact-us/
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.