This is a related problem, but not the same... however I think this solution may work for 4 series too. In a 3-series I have the same "Link Lost" problem with the communication with a HomeworksQS system. We install this kind of configuration in almost all of our projects and never happened to us before. What other behaviours I notice are:
1. After uploading program it works fine.
2. If I reboot the system, the Link Lost appears and the communication can't be reestablished until I upload program again.
3. If I connect to the CP3N just before the program starts, when it does the connection is successful and about the time some touch panels reports themselves in the console, I got the Link Lost.
4. We have a very similar problem with CP4N, but in that case, we can reboot the system and it works.
5. It works flawlessly in a 2-series.
So, the workaround I found is to wait 60s to establish the communication after the reboot. What I think is happening (at least in the 3-series) is that the system does some initial tasks with the TCP stack that breaks this older kind of connections, so the idea is to wait until everything is done and then connect the third party system. I use a simple delay in Simpl, between the signal that establish the communication and the TCP Client. Try that with your 4 series system, and let us know if it works.
clemare
