I have the same problem. I installed the server on a Ubuntu Server 16.04, version 2.2.1 it is NGOCS and I have downloaded the Windows agent in version 2.1.1.3.
I have tried every possible connection, I refer to the URL of my server. In the end, after many trials, he has given me the following report:
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Starting OCS Inventory NG Agent on Thursday, July 21, 2016 18:53:19.
AGENT => Running OCS Inventory NG Agent Version 2.1.1.3
AGENT => Using OCS Inventory NG FrameWork Version 2.1.1.3
AGENT => Loading plug-in(s)
DLL PLUGIN => Searching for Plug-in DLL(s) in folder <C:\Program Files (x86)\OCS Inventory Agent\plugins>
DLL PLUGIN => 0 DLL Plug-in(s) successfully loaded on 0 DLL(s) found
AGENT => Using network connection with Communication Server
COM PROVIDER => Loading Communication Provider <C:\Program Files (x86)\OCS Inventory Agent\ComHTTP.dll>
AGENT => Using Communication Provider <OCS Inventory NG cURL Communication Provider> Version <2.1.1.3>
AGENT => Sending getLabel request
COM SERVER => Initializing cURL library for getFile
COM SERVER => Using cURL without server authentication
COM SERVER => Disabling cURL proxy support
COM SERVER => Enabling cURL SSL server validation support using CA Bundle <C:\ProgramData\OCS Inventory NG\Agent\cacert.pem>
COM SERVER => Sending fileGet request to URL <http://192.168.1.15/deploy/label>
COM SERVER => fileGet response received <HTTP Status Code #404>
COM SERVER => Cleaning cURL library
AGENT => Failed to retrieve Label <HTTP Status Code #404>
AGENT => Sending Prolog
DID_CHECK => Read DeviceID <PCxxx-2016-07-20-18-14-34> and MACs <xx:xx:xx:xx:xx:xxxx:xx:xx:xx:xx:xxxx:xx:xx:xx:xx:xxxx:xx:xx:xx:xx:xx> in file <ocsinventory.dat>
COM SERVER => Initializing cURL library for sendRequest
COM SERVER => Using cURL without server authentication
COM SERVER => Disabling cURL proxy support
COM SERVER => Enabling cURL SSL server validation support using CA Bundle <C:\ProgramData\OCS Inventory NG\Agent\cacert.pem>
COM SERVER => Sending HTTP Post request to URL <http://192.168.1.15>
COM SERVER => HTTP Post response received <HTTP Status Code #200>
COM SERVER => Cleaning cURL library
AGENT => Prolog successfully sent
SUPPORT => No support detected, Registration key : N/A
AGENT => Prolog Frequency set to 10 hour(s)
AGENT => Unloading communication provider
AGENT => Unloading plug-in(s)
AGENT => Execution duration: 00:00:01.
I can not find solution in any log.
I disabled the Windows firewall.
Will it affect you have activated corporate antivirus?
Regards