A redirect and such happens due to
The design of the web+internet. It's not a sign of an infection but as you know (you will know as you learn more?) that many users will think it's an infection.
That may be good news for companies that do support for money. It doesn't mean they can fix the web but it does mean they will be in business for a very long time.
Here's an article about a rare issue. -> https://www.google.com/search?hl=en&as_q=router+dns+hijack
It's still rare to me since I've only encountered it once.