No wired internet and can´t power off Ubuntu 18.04.01 LTS.

[matheusmel0]

I´ve just downloaded Ubuntu for the first time. Unfortunately, I am unable to use it as it can´t connect to the internet (wired) and added to that every time I restart or power off the PC it justs gives me a black screen and I have to force it to power off. It didn´t present any error during boot or installation, though.

[Autodave]

Some specs on your machine may help us.

Did you happen to try the internet while you were on the boot medium?

[franknfurter2]

It's a pitty, that your first try using ubuntu ends up that way. But be ashured, that ubuntu is a well maintained system and we will find a solution for your problem.
But like Autodave said, we need more details about your hardware and the installed drives and network card.