network interface down after boot

Hi. I am on my way to setup ethercat with linuxcnc. I managed to get to the point where ethercat is working and now I am trying to connect it to linuxcnc... However, I suspect something is wrong and I would kindly ask for opinion: My computer has two ethernet interfaces. I use one for connecting to the internet and the other for ethercat. Every time I boot the computer, the internet connection works fine but I have to always manually bring up the interface that is used for ethercat. After I do this, everything looks ok. I tried all sorts of things to automatically bring up the ethercat interface during boot but nothing works. I also noticed that during the boot, the process of bringing up the interfaces take a bit longer than what I am used to (20 seconds). Does anybody know what could be wrong.

Thank you,
Jan

I think this post will solve your issue
forum.linuxcnc.org/ethercat/45336-etherc...-step-by-step#241740

I carefully followed your instructions when I first installed Ethercat. And I didn't have this issue for a while. Then, something changed and I don't know what. I once again made the udev rule but it didn't help. I am tempted to reinstall the whole thing but this is not the way to do it, I guess.

I'm sorry its not working for you.

I'm not quite sure on the detail, but the other way I fixed this before I worked out how to use the repo was to start the service on startup. 
The methods I found on google to do this involving a service file did not work for me so I probably upset the purists.
I gave my user rights to run sudo without using a password and started the service in my .profile file.

in the ethercat config file (etc/default/ethercat) exists an if up section, you can try to add your interface there to, to force an getting up from the interface.

Thank you very much for your kind help. I now better understand what is happening. There is nothing wrong with Ethercat module but I obviously don't know how to setup the network interfaces properly. If I use Network Manager then everything works fine but when I uninstalled it, it stopped working - the network interface used for ethercat remained down during the boot. For the internet to work, I added the following two lines to /etc/network/interfaces

but to bring the other interface up (eth1) during the boot I would obviously have to do something else. I tried all sort of things but nothing worked. I would love to get rid of the Network Manager so if anyone has an idea what to do, I will remove the Network Manager again and try it out.