Windows Server 2019 build 17733, fresh installation from .ISO, activated.
Install Windows Admin Center 1808, from offer by Server Manager.
In EventViewer not exist any events for this problem (or in this time).
With "Windows Admin Center 1803" all work.
Today WAC recieve update to version 1809, but error exist:
About Windows Server:
Hyper-V VM at Windows Server 2012 R2 Datacenter Edition.
This is a known issue with Chrome. They have a bug regarding NTLM authentication and websockets.