Firstly, I will suggest you to do Windows Troubleshoot for Error Code 800f020b. After that, Disable the proxy internet connection and try again to install windows update.
Repair and Solutions for Error Code 800f020b
They failed for windows update services that could also cause you this Error code 800f020b while updating Windows update .
Try the below steps to repair Windows services
Repairing Windows update services is not possible like you repair any windows apps from the add/remove programs. There is a procedure that you need to follow through command lines. Above all, this requires the user to have administrator rights on his computer. As per the Microsoft set of rules defined on various Knowledge base articles, the steps are simplified as mentioned here to reset your windows update services.