Vray is displaying this message, happened suddenly while working on a file. Vray and vrlserver are both updated to the latest version, license info is correct in the edit/set license server dialog.
There was some latency in the backend for several minutes, should be OK now. Check if you see your license when you navigate to http://localhost:30304 on the license server machine and if yes - restart 3ds Max if you still have the issue.
As everything was working fine, out of a sudden I got the same -200 error. I tried restarting my PC several times, reinstalling Vray, WibuKey drivers and the license server. http://localhost:30304 gives me an error: “This site can’t be reached”. I checked the Windows services and VRLicense was stopped. I tried to start it but it won’t let me - “error 1053”. 
Thanks, Mihail. The Problem is solved now. 
@Mihail_Kuzev_1 Thank you for that solution - it works!