0x80072EE2 Network Connection: Windows Update Agent encountered transient network connection-related errors

I´ve been working last 2 weeks with one ConfMgr 2012 R2 CU4 enviroment installed on Windows Server 2008 R2 & SQL 2008 R2. The problem is, that SUM stopped working there.

1. I once re-build their SUM by uninstalling WSUS+SQL DB+IIS site and re-done everything. It worked for a month but then broke apart with error code 0x80244010 & 0x87d00631. Here I suspect that this happend after adding lot of additional fixed which might overload the server (not a normal case, I know).

2. Yesterday I re-build the server, but the job was unseccsessful. I had lot of broke connections to IIS and there was WSUS Api failure to IIS. There was errors in log at the start of first sync and whole installation seemed unreliable to me. During this situation, none of client received deployment policy of updates and they stayed as unknown/gray to the deployment.

3. Today, I uninstalled everything SUM releated and re-build everything again. No errors in logs during installation on sync process. During the client deployment, none is green/yellow, but clients started to appear in red, as error;

0x80072EE2 Network Connection: Windows Update Agent encountered transient network connection-related errors

From client-side I see 2 different errors in scanagent.log;

Case 1:
;ScanJob({9BBF0F5A-2087-4E91-84B6-82433740D184}): CScanJob::OnScanComplete -Scan Failed with Error=0x80244010 ScanAgent 19.1.2016 16:46:07 5424 (0x1530)
ScanJob({9BBF0F5A-2087-4E91-84B6-82433740D184}): CScanJob::ScheduleScanRetry- ScanRetry Timer task successfully scheduled. Will wake up in next 1800 seconds ScanAgent 19.1.2016 16:46:07 5424 (0x1530)
ScanJob({9BBF0F5A-2087-4E91-84B6-82433740D184}): CScanJob::OnScanComplete - Scan Retry successfully scheduled ScanAgent 19.1.2016 16:46:07 5424 (0x1530)
ScanJob({9BBF0F5A-2087-4E91-84B6-82433740D184}): CScanJobManager::OnScanComplete- Scan has failed, scan request will be pending for scan retry cycle. ScanAgent 19.1.2016 16:46:07 5424 (0x1530)
CScanAgent::ScanCompleteCallback - failed at OnScanComplete with error=0x87d00631 ScanAgent 19.1.2016 16:46:07 5424 (0x1530)

Case 2:ScanJob({10B84774-D63A-4985-8141-37A20634B272}): CScanJob::OnScanComplete -Scan Failed with Error=0x80072ee2 ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)
ScanJob({10B84774-D63A-4985-8141-37A20634B272}): CScanJobManager::OnScanComplete- failed at CScanJob::OnScanComplete with error=0x80072ee2 ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)
ScanJob({10B84774-D63A-4985-8141-37A20634B272}): CScanJobManager::OnScanComplete -ScanJob is completed. ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)
ScanJob({10B84774-D63A-4985-8141-37A20634B272}): CScanJobManager::OnScanComplete - Reporting Scan request complete to clients... ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)
- - -Evaluating Update Status... ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)
- - Calling back to client on Scan request complete... ScanAgent 19.1.2016 16:33:20 3444 (0x0D74)

Additional info: This case is from the same enviroment where I had problems with SUM in OSD before: https://social.technet.microsoft.com/Forums/en-US/2d1bbfb1-3fe7-4d97-9f2d-b485216947c1/install-updates-fails-0x80244010?forum=configmanagerosd