Error message.

I'm not the network expert.
Are you sure you are using "Ethernet connection 1"?

I have no idea if i'm using it.
How to check which connection i'm using and how to get to those settings?

If "Ethernet connection 1" is the only one you can choose to edit then that it the only one that can be used, I guess.

[edit]

maybe reboot?

That's the one i've created. I had them before, but after installing some sort of network management program all networks disappeared.

I've posted screenshot earlier.

No i can only create connections.

"Ethernet network"
"Device not managed"

Does not look good to me. But it's rather difficult to troubleshoot from afar.

Maybe this could be a solution:
askubuntu.com/questions/71159/network-ma...s-device-not-managed

see first answer.

As an alternative backup your config to a usb-stick and reinstall.


[edit]
I do find it somewhat strange that you felt the need to install another network manager. I recall installing the Linuxcnc ISO a while ago and the preinstalled network manager worked just fine. (ie right click on the icon in the top right corner on the desktop to edit the connection)

I've reinstalled Debian and updated to the latest version. 

All connections are back. Look this is what i'm getting now. I can even connect to the mesa board but when checking it it says it's not online.

P.S. Getting that new manager was dumb.

I would have set the netmask to 255.255.255.0

Did. Connection is there.
But i cannot connect to the card for some reason. He can't detect it.

you mean you can ping the card on 10.10.10.10?

No i cant ping it. I mean i can see life in them and i know that LAN port is working. I think that i need to figure out how to set it properly.