Proxmox installation with Realtek 8125 device.

setup.sh

# root@pve2:/etc/apt/sources.list.d# lspci | grep -i real
# 08:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. Device 8125 (rev 05)


# boot up with "DEBUG" mode
# ctrl-d for the first prompt

# connect another thethering network ...
ip addr show
ip link set enp12s0f3u3 up
dhclient enp12s0f3u3
ping 1.1.1.1

##########

chmod 777 /tmp
apt update

vi /etc/apt/sources.list
# add this line: 
# deb [trusted=yes] http://download.proxmox.com/debian/pve buster pve-no-subscription

apt install wget
wget http://download.proxmox.com/debian/proxmox-ve-release-6.x.gpg -O /etc/apt/trusted.gpg.d/proxmox-ve-release-6.x.gpg

apt install pve-headers-$(uname -r)
apt install vim wget build-essential dkms


lspci | grep -i real

wget -k https://get-the-driver-from-realtek/r8125-9.005.01.tar.bz2
# when I'm trying here the official realtek site does not allow me to download it. error code 404
# got it from https://build.opensuse.org/package/show/home:Sauerland/r8125

tar -xvf r8125-9.005.01.tar.bz2

cd r8125-9.005.01
chmod +x autorun.sh
./autorun.sh

# ctrl-d to exit. 

##########

# install with turning off automatic reboot after finish installation. 

##########

# back to the console: ctrl+alt+F1? F2? F3? F4?

lsblk
# find the pve root. not remembering precisely. 
mount /dev/pve/root /mnt

cp ~/r8125-9.005.01.tar.bz2 /mnt/root

# reboot. 

##########

# your first bootup. 

ip addr show
ip link set vmbr0 down

# activate tether 
ip addr show
ip link set enp12s0f3u2 down
ip link set enp12s0f3u2 up
dhclient enp12s0f3u2
ping 8.8.8.8

vim /etc/apt/sources.list.d/pve-enterprise.list
# deb [trusted=yes] http://download.proxmox.com/debian/pve buster pve-no-subscription

apt update
apt upgrade
# --> there's kernel update. pve-headers will not match correcly. 

apt install pve-headers-$(uname -r)
apt install vim wget build-essential dkms

reboot

##########

ip addr show
ip link set vmbr0 down

# activate tether 
ip addr show
ip link set enp12s0f3u2 down
ip link set enp12s0f3u2 up
dhclient enp12s0f3u2
ping 8.8.8.8

apt install pve-headers-$(uname -r)
apt install vim wget build-essential dkms


tar -xvf r8125-9.005.01.tar.bz2

cd r8125-9.005.01
chmod +x autorun.sh
./autorun.sh


ip link set enp12s0f3u2 down
ip link set vmbr0 up
dhclient vmbr0 

reboot