Hi, looong time user here (have one of those never expiring keys). I'm having the exact same issue. Also using Malwarebytes along with Bitdefender and started experiencing random internet drops on my PC about the same 3-4 day time frame. Yesterday I decided to just close out of Malwarebytes after I lost connection and discovered I would have connectivity back. Now I know it is exactly Web Protection from the OP so I will go ahead and disable that for now. In case the OP never returns with his log file I have gone ahead and included mine.
mbst-grab-results.zip