When trying to optimize the network settings, I lost access to the system.
Just for info I did change the trunk msu from 9000 to 9014 and I could not access the system since. Do not think so, but it could be an network issue as well. (my idea was that an source msu needs a somewhat bigger transport msu)
What ever I am looking for a way to restore the previous config, without reinstalling the system.
In pfSense there is an option to add an usb with the config and just reboot. But I am not aware of an option like that for TrueNas. Could not find a console option for that as well 
So I hope that that kind of option exists.