I cannot and never could access a safe address to enter my router

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HTTP error 401 occurs whenever you fail to enter the username or password correctly when logging into a website. Websites are sometimes referred to as portals. All modern consumer routers have portals that one can log into for administrative purposes.

I apologize if you already know the following but there are two kinds of passwords maintained by a Wi-Fi router. There is an administrative password which is used to log into the router's portal, and there are password(s) for connecting to the router's Wi-Fi network(s). My hypothesis is that you are having troubling logging into your router because you are entering the Wi-Fi password instead of the administrative password.

You didn't provide the model of your router, so I can't give you specific instructions for changing your administrative password, but it's not in the same place where the Wi-Fi password(s) are set. You should definitely change the administrative password to reduce the chance that hackers gain access.

Constructive comment: Proofread your writing before posting. Everyone can be forgiven for making a few typos, but it was not easy to make it through your writing.