Hi Szabo
I am Dave, I will help you with this.
That yellow exclamation mark indicates the network card device driver is not installed correctly, the best option is to go to the support page for your PC on the manufacturers website, then from there, download and install the version of Intel network card device drivers they recommend.
If you have any difficulty locating the support page, click your Stat Button, then just type msinfo and press Enter, please provide a screenshot of the resulting System Information window.