Xbox One connection problems. I can't get assistance from Microsoft (Italy). I beg your help!

Hello to everyone!

I've got problems connecting my Xbox to internet since last week, and I really don't know why. Internet is working, even on my Xbox 360. It actually is connected to the router, but says there's no connection to internet.

I tried the connection test step by step, it didn't work (I skipped when they talk about DHCP not allowed from the router 'cause i don't know what it is, but 'till the day before it perfectly worked, and i don't think that the router setting changed). Microsoft assistance here in Italy doesn't assist (sorry, but that's true) and so i really don't know who to ask help, but maybe it's not the right place to talk about it.

Note: what's weird is this:

-if i try playing an xbox game pass game obviously it doesn't work, due to the lack of connection

-if i play most of the owned (and installed game) everything goes on as if there's no internet

-if i play the whitcher 3 GOTY, that i own, seemingly it connects to internet, all the menues and dashboard shortcuts appears (diffrently from when there's no connection), the promos in the dashboard appears, and the xbox has even found some minor upddates, that were put in download list, but didn't started (still they has been downloaded by the two next day while off).

-if i play any app, menu or game after having done what in the last point it returns to absolutely no communication with internet like before (so in the dash it goes back to only show last used apps, the menu "your games and apps" and the suggested apps.

So I don't know what to think...it's a bug? is something broken? what can i do?

Really, I repeat myself, but please, help me!

Thank you in advance!

:)