Ok, it seems r8168.aspm=0 or r8168.eee_enable=0 cannot be set with the grub customizer, but found another way:
sudo geany /etc/modprobe.d/r8168-dkms.conf
add the following:
# Disable Energy Efficient Ethernet
options r8168 eee_enabled=0
# Disable Active State Power Management (ASPM)
options r8168 aspm=0
Then save and close geany, then run the command:
sudo update initramfs -u
Then reboot
sudo reboot
After the reboot you can verify that the energy efficient ethernet is indeed disabled with
sudo ethtool --show-eee enp2s0
replace enp2s0 with the name of your Ethernet interface. You can get the name of your interface with the "ip a" command
If ethtool is not installed do:
sudo apt update
sudo apt install ethtool
I'm now running an endurance test with EEE disabled. Will report back here.
