No connection to W2K12R2

Make sure you are using port 8530 for the WSUS server, assuming of course that the WSUS server and Solarwinds PM are on W2K12R2 as well.

Just a thought.

can you digress on what you mean by "not able to get a connection"?    Do you mean they aren't showing up as WSUS clients, or that running a task like Detect Now/Inventory/update deployment/etc... is failing?   if the latter - any error messages displayed?

First of all, when i add a W2K12R2 server in "First Time Usage Wizard", it hangs in "Gathering information from selected..." and takes a long time until it says "not able to manage".

Source: SolarWinds.PM.UI.Wizards
Exception occurred at 30.03.2017 09:23:40: The task and operation were aborted.
Stack:    at SolarWinds.PM.UI.Wizards.Helpers.TaskHelper.IsTaskSuccessful(String fqPath, Guid taskId, String& message)
   at SolarWinds.PM.UI.Wizards.Workflow.Configuration.WMIProviders.Execute(ClientDevice client, Boolean& cancel, Action`1 progressCallback)

Afterwards, the server appears under "Unassigned Computers" and most of them send a report as well, some still don't.

It is also possible to get the System Information, Services but neither Windows Update Scan nor Windows Update History.

For information, our installation routine for the W2K12R2 servers is always the same. Operating System, drivers and needed

services. After this we install Symantec Endpoint Protection.

WSUS server port is 8530 of course.

In WSUS dashboard i can see the last report.

Hmm... OK.    

So Patch Manager uses some extended WMI calls to pull back some of the data.   To be able to do that, it attempts to put a WMI Provider on the target machine.

Perhaps that isn't getting installed.

Here's a test i would recommend: 
Target one of the machines you are having an issue with, then right-click it and run the "Check and Manage Computer Connectivity" task.

Set the settings in that task like this:  

and then run that.

I'd be curious if you give it a few minutes, then go look at Task History if that task shows an error or if it comes back OK.  

If it comes back OK, go back to Computer Explorer for that machine and see if you get the same issue.

so, i did the steps you mentioned. After a minute, i get this error message but the Solarwinds  clients components have been installed successfully.

Details:
Successfully connected to WMI.
Hostname is HO0CRIN42DK.de.bosch.com


ICMP Ping succeeded.
Unable to retrieve MAC address of 10.7.249.159. Error Code: 0x80004005 Message: GetMACAddress()::Error retrieving MAC address for 10.7.249.159. Error Code: 67

Unable to retrieve NetBIOS domain name and computer name.


Successfully connected to the Microsoft Endpoint Mapper (Port 135)


Successfully connected to direct hosting NetBIOS over TCP-IP port 445 which is required for 'File and Print Sharing'


The computer (HO0CRIN42DK.de.bosch.com) does not have the EminentWare WMI Providers installed.
Message: Invalid namespace

Successfully connected to WMI and retrieved operating and computer system information.SolarWinds Provider Required: True
Microsoft WMI Redistributable Required: False
Provisioned the SolarWinds Client Components on HO0CRIN42DK.de.bosch.com

Structured Exception: Error Code: 0x80004005

i also checked the following things.

• Verify you can ping the remote computer by name from the Patch Manager server. - YES
• Verify the account specified in the error is a local administrator on the remote computer. - YES
• Verify that you can connect to the remote computer's admin$ share with the account specified in the error: - The command completed successfully. I see a mapped drive. YES
• wbemtest retrieve WMI Information from client    YES

very curious

I'd agree.. that is very curious!

If you have access to the remote machine via RDP - if you look under the Control Panel at installed software, do you see SolarWinds Client Components listed in there?  Typically if the WMI provider got installed successfully, that's how it would show in the list.

Yo, Client Components have been installed successfully. If i remove them, then they will be installed again and Wizard goes until it waits for the Report from the client. Unfortunately, it doesn't get any in time.