This reminded me a problem that I have seen almost 17-18 years ago. There was a file that we were trying to download but it was just being interrupted during download process. When we tried to download the file on another computer, it was fine. Long story short; we changed the ethernet card of that computer and it started downloading file. I don't remember all the details; but probably something wrong witj ethernet card driver.
I am not a FAANG engineer but I hold a Ph.D. (computer science). I completed my Ph.D. in 8 years while I was working in the private industry. During this time frame; in my private life, I became a father ;) And, at work, my responsibilities grew - from being a developer to being a manager.
I came close to quitting my Ph.D. many times and many of the fellows - who were also working in private industry and doing Ph.D. - quit in a couple of years.
I know the problems you mentioned are not the same as the ones I mentioned. What I am trying to say is; if you have some kind of stubbornness - and also you like to research, you just start and stick.
I can't say I feel dumb(er) but I can certainly say that when I am stuck with a problem, I feel the urge to use pen & paper (s-pen & s-note) to work on the problem ;)