Well, you did not waste our time. You really did not give us any information to make any suggestions - for example, we have no clue what version of Windows, how you connect to your network, or anything about your hardware - only that it might be a notebook.
I suspect since this problem started after a format that the newly installed drivers were generic with default settings and over a period of time, they were updated and optimized, based on your usage. At least that's my best guess - but it assumes everything else was fine (i.e.; Ethernet cables are good and securely fastened, router port is good, and the computer worked fine otherwise).