Network Bug in ethernet cable connection on Ubuntu desktop version with IBM Power architecture [closed]

Good evening, I am writing to you from Italy and I use a translator because I do not speak English fluently. I have a machine based on IBM Power 9 on Raptor computing System motherboard, I installed your Ubuntu version 20.04.02 LTS and to use it in desktop mode I installed a graphical environment. During the main Ubuntu installation, everything went fine and he did as all distros do, saw the connected ethernet port, set it up and made it work for him. Doing the test ping and trying to install from the terminal in server mode, no problem, everything normal, everything works fine and interrogating the system, he reports the connected port and all the data detected as an IP address and everything else. As soon as I installed Gnome, or even XFCE or even KDE PLASMA, or canonical graphic environments that we all know, a big problem arises. Ubuntu does not recognize the cable connection and consequently tells me that I am offline. The beauty is that if I try to navigate in the browser, then everything is ok, browse and download files regularly, if I try to download files or install applications via the terminal, everything is fine, if instead I try to download applications or updates from the software center or I try to configure Evolution Mail for example, then it tells me I'm offline and doesn't allow me to do anything. In the icon at the top right, where you see the connection with the three small squares, I see a cross on the one on the right and it says disconnected. I try to connect but I get nothing. Ultimately I think there is a bug when installing the graphical environment, which does not allow Ubuntu to see more, the connection which instead is regularly connected and fully functional. Another problem that I have been experiencing for a long time is on Firefox, the bookmark says that it cannot work because there is a conflict with the security software used by Ubuntu and is therefore disabled. Thunderbird does not open preferences and therefore cannot be configured. All problems encountered from version 19.04 to 20.10 that I tried some time ago. Finally, it should be noted that for 2 times, when I used version 20.10, at a certain point in the Gnome graphic environment, almost all the application icons disappeared, almost all those in the favorites bar and on restart, after it loads regularly the Kernel and log in, Ubuntu no longer starts and always comes back to login. The latter seems to be another big bug in the graphical environment, therefore not related to the Kernel. Is there anything you can do to help me and to fix these bugs that Ubuntu in the Power version has been carrying on its shoulders for years now? Thank you

Solution 1:

Both netplan and Network Manager are competing for control of networking. I suggest that we amend the netplan file to defer to NM. First, we'll back up the currently working file:

sudo mv /etc/netplan/*.yaml  /etc/netplan/ubiquity.bak

Now create a new file:

sudo nano /etc/netplan/01-network-manager-all.yaml

Add the following:

# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager

Netplan is very specific about indentation and spacing; proofread carefully twice. Save (Ctrl+o) followed by exit (Ctrl+x).

Reboot. Is there any improvement?