Wrong URL Redirects to the router homepage

Hello,

I have noticed that, every time on my home network when I have a dead/wrong url, I'm directed to my router homepage. The most wierd part is that it doesn't require the admin password. I can configure the router there directly.

I changed the routers twice (different brands) and it is still the same. So what is it that I'm doing wrong ? Somewhere my configuration is incomplete in the router.