[Help] Ethernet Issues with AMD System.

Hello, this is my first post here.

My system specs are:

-FX-4300

-GTX 760

-GA-78LMT-USB3 (rev. 5.0)

I'm trying to install the new Catalina using these two guides (1 and 2).

I've used the RTL8111 kext, tried to disable EEE, tried other versions and forks, but it just don't work.

I can boot the installer without problems, but when I try to install, it says that an internet connection is required in order to install macOS. I tried to ping in the terminal as well but it doesn't work too.

The led on the lan port lights up (GREEN is continously active and ORANGE blinks sometimes).

I also tried to boot into the mojave installer, and the same problem occurs. HOWEVER, about a year ago I installed High Sierra and it worked just fine.

This is all information I have and I can also give logs if necessary. I hope I can solve this problem.