I recently reinstalled, I previously had no such issues with any distro I tried (including endeavouros).
When I boot my computer 8 times out of 10 internet either doesn’t work or, if it does, the pink is absurdly bad.
A friend suggested I try using connman instead, that did not help.
When it connects to the internet well everything is fast and flawless.
Bro, reading the first part in italian tripped me hardcore. I got so confused. I initially thought that you answered in italian because I posted in italian myself.
You have Realtek 8168 hardware. I’d try uninstalling package r8168 and reboot. If that doesn’t help anything, you can re-install it easily (it should be in the package cache: ls -l /var/cache/pacman/pkg/r8168*