Why doesn't the KMS client find the KMS server?

Question

System administration

I am transferring an organization from MAK to KMS in Office 2010 and 2013.
I set up a KMS server. Created (it didn't create itself) _VLMCS record in DNS.
I waited for the money, tried to activate it on the client, in order to at least see an error that the counter had not yet reached. But to my surprise there was an error:
ERROR CODE: 0xC004F074
ERROR DESCRIPTION: The Software Licensing Service reported that the product could not be activated. No Key Management Service (KMS) could be contacted. Please see the Application Event Log for additional information.
When I set the command ospp.vbs /sethst on the client, as expected, there was an error with the counter, that is, the KMS client found the KMS server

Answer 1

I screwed up with the port in the _VLMCS entry :)
Although a very useful article: https://support.microsoft.com/ru-ru/kb/2870357

Answer 2

1. Try to install the activation server manually:
slmgr -skms
2. Is port 1688 available on the KMS server?

Answer 3

I am writing for those who also encountered this: Dig first in various firewalls on the KMS server, or between the client and the server. In my case, it was the Application Control program from the VipNet package - it did not issue a request until I explicitly launched the application interface - by default it was "prohibit applications from working with the network with a user request", but the request for network access for the user was issued only when Application Control is explicitly launched, but the prohibition of working with the network did not allow the client to detect the KMS server. When I explicitly allowed networking in the program, everything was activated instantly. Lost half a day because of VipNet's "application control" bug. To check, you can use ping on the server IP and telnet IP 1688 - if the ping goes on and the telnet does not connect to port 1688, then