Re: VNC viewer shows black screen without VPN access only

I do not know anything about the Siemens HMI screens, but your problem 
sounds like an authentication issue.  If the VPN is direct to the 
Siemens HMI screen, then that is used for the authentication.  Check the 
server Security & User/Permission settings for VNC Server on your 
Siemens HMI screen, then try matching them on your VNC client.

Good Luck

*Patrick Shoaf*
IT Special Projects
[email protected]

On 12/3/2021 9:50 AM, Thomas WILLIAMSON wrote:
> Hello,
>
> I access to a Siemens HMI screen which natively includes a VNC Server.
>
> I get a black screen when connecting either with TightVNC or VNC 
> Viewer. After a few seconds, the VNC connection ends up and the viewer 
> stops.
>
> Surprisingly, if I connect through a VPN access from a public network 
> (Forticlient VPN), the display is correct and I don't get any black 
> screen at all.
>
> I have tried to modify several parameters from the VNC client, such as 
> encoding type, colors, display size, etc. which usually help to 
> resolve black screen issues, but nothing helped.
>
> Any idea on potential causes and things I could test?
>
> Thanks!
>
> Thomas
>
> --
>
> <https://www.eauxdevienne.fr/>
>
> 	
>
> Thomas WILLIAMSON
>
> *Technicien Systèmes et réseaux*
>
> Service Exploitation, Systèmes et réseaux
>
> Siège administratif - Poitiers
>
> *Tél.* 05 49 61 25 25 | *interne *: 2235
>
>
>
>
>
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