I was cleaning out my laptop and getting rid of some junk when I found an old batch file I had written to repair LAN connections. It works great, but only releases/renews the IP. Just save the code below as a .bat file and execute it in Windows whenever your Internet is acting up.

@ECHO OFF
TITLE Repair LAN by Paul Stamatiou
ipconfig /release
ipconfig /renew
ECHO.
ECHO LAN IP REPAIRED.
ECHO.
PAUSE
CLS
EXIT