@casino Previously you reported a problem very similar to this. Instead of losing safe search, you weren’t able to access some web sites, and the gravatars on pcwrt.com disappear on a periodic basis. You said “There’s a site that doesn’t work every 5 minutes”. Has that problem gone away?
There are two similarities between the problems:
They both occur periodically, which cannot be attributed to the router. Because there’s no timer on the router to switch the problems on and off.
We cannot reproduce either in our controlled test environment running Windows XP and Chrome. If there is a problem with the router and Chrome, it should be reproducible on another computer.
Please understand that the router has no knowledge whether a browser is in incognito mode or not. In fact, it doesn’t even know if a request comes from a browser or a Windows system service. Therefore, it’s impossible for the router to behave differently based on the browser mode. Considering that you are running an old system, there is possibility that some programs are running on it without your knowledge.