The cable that comes with the unit is a boosted cable - that is why it only works in one direction.
If you need to use a longer cable, make sure that it is not just a standard long HDMI cable and include some kind of boost. Alternately, use some HDMI extenders and run some standard category cable between them. This is relevant to all HDMI connections, not just those to a Cisco TelePresence endpoint.
There is a Cisco 9m long cable you can purchase too which was made specifically for the Room Series endpoints - the CAB-HDMI-MUL4K-9M=. Another advantage of this cable is the multi-head it has on it to allow connection to different types of devices.
Wayne
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