Losing Ethernet connection randomly
I'm here again, this time with a strange question...
We maintain the IT infrastructure in a school. We have multiple buildings in the school campus. We have a PRIVA Systems - HVAC building automation system & remote controller (industrial PC's).
In one building, lets say the main building, we have the main automation system to manage the HVAC, it controls al the heating and air flow systems.
The maintenance engineers can remotely log in into the system via TeamViewer app or Windows Remote desktop from a system in our maintenance office which we can likewise manage the system.
From the beginning we have had problems with the office system and only that one PC. Sometimes the PC looses the connection with internet, yet the PC is still running.
We can't ping the PC and we can't connect by RDP nor can we connect by TeamViewer app either... nothing.
It has a fixed IP address, all settings are normal... no strange errors or whatever in the logs...
The PC went back to the manufacturer, they checked it over a time of 2 months... in that time we hooked up an other PC with the same settings as the original... and guess what! No problems at all !!
The manufacturer didn't find anything on there side as well...
Now the big issue is: They say (firm that installed the industrial PC): It is your fault if the device is't running properly cause it is an internal network issue...
We can't find anything .. the strange thing is that the laptop workes fine with the same settings...
The industrial PC (PRIVA SX100) runs normal over several weeks, than suddenly no connection, sometimes it runs for 2 days, sometimes 4 ... before the "error" occurs..
What is your suggestion?
okay we can replace the %#*@ thing .. but we have to find the problem so we can explain it to several interested parties. (and pay the cheque or.... :) )
Can I check a specific log? ...
All the power options are set to never sleep. Also the network adapter power options are set to never sleep.
There is one thing that I noticed :
We saw that the secondary DNS was causing trouble, so we deleted it and only fill in the primary DNS what is, in this case, the same as the default gateway.
Secondary DNS is given by the ISP.
When we removed the secondary, the PC was going well, when it failed again and rebooted the pc, we saw that the secondary DNS was back... how is this possible?
Can this be the major problem?
Thanks in advance!