OPEN VPN Server configured for streaming, but some clients getting black screen. How to troubleshoot.

[sharingmaxi]

Hi all,

I have OPENVPN server configured for group of people who are using it to connect with a openvpn client so they can watch streaming content.
We have a strange situation in Italy where for 50% of users it works fine, for the rest it does not work.
Even they are connected successfully, they can see only black screen, and no content.

I would say that my configuration is wrong, but then how for other users it works with no issues.

Does anyone have idea where to start troubleshooting or should I pay attention to something specific in configuration?

thanks