WinCC Server with 3 clients worked perfectly for three months and then stopped, when I try to open project from client, I get a message "Server not available".  

We checked everything, Runtime project is active on Server, checked Simatic Shell settings (clients and servers are visible from all Simatic shell), reapplied Security settings with SIMATIC Security Controller, tested with different users, project path on the server is reachable from the client. We contacted Tech support, sent them log files and tried everything they sugested, to reset wincc and delete some files from the Tia project folder, to create new empty project, even with new project, error is the same.

I suspected that the problem is that we connect with Remote Desktop to the server, as I read later it is not supported for WinCC server unless if using Service mode. We tried to start Runtime project in Service mode, reboot the server and then connect to server with the Service mode user, but still clients cannot connect.

If someone had similar problem, please let me know what else we can try.

Hi janja,

 Thank you Hazard_7,

We tried and checked all these items and still no luck, we get the same error. 

Hazard_7

Hi janja,

The following workarounds or solutions can help:

• After entering the IP address of the other system as multicast proxy and increasing the TTL (time-to-live) in the SIMATIC Shell, the WinCC client can successfully connect to the server project.
  
  

• If necessary, you can see in the Windows events of the WinCC server that the server system is overloaded and that the WinCC server has switched to error mode.
  

  Error   15.11.2021 01:57:38 RedundancyControl 257 (1)
  Setting state to FAULT because of long system overload

  
  This means that it would no longer be possible to connect to the WinCC server.
  After the performance and hardware of the WinCC server have been improved, the problem has no longer occurred.
  
  
• SIMATIC LOGON was activated in the multiuser project, but not installed on the WinCC client.

• Project path to server project is configured by IP address instead of UNC in the Autostart tool and thereafter a manual interconnection is performed via SIMATIC Shell 

Thank you Murof,

I didn't configure lmhosts files but there is a DNS server configured in the network, and name resolution seems fine, server and clients are all accessible between each other by name.

Murof

Hello Janja

Do you have configured the lmhosts files on all systems?

its very important that you do it like in this FAQ:

https://support.industry.siemens.com/cs/de/en/view/108464289

Only if you work with an DNS Server the name resolution should also work without but this could also be a reason for a deisconnected Server

Bye Murof

So, we discovered when the problem happens, but not why. It seems that this error appears when server is restarted.

We reinstalled complete virtual server and installed TIA Portal + WinCC Prof again, and made a snapshot of the virtual machine. When we started the project, the client works. Then we did a restart of the server, and then the "Server not available" message appears again on the client. We tried 3 more times, to restore from the VM snapshot, and every time the client works until the restart of the server. This is why this happened in the first place, server worked for 3 months without restart, and after first restart, the clients crashed.

Does anyone have idea why this is happening? Server should be able to restart regularly, right? We even properly shutdown Runtime on server and the client before restart.

What could be changed in the server configuration after restart, that completely damages server-client connection?

Thank you for your help!