Work through it in this order: input selection, then the handshake, then bandwidth, then the cable. Swapping the cable first is the common instinct and the least likely cause.
1. The obvious one, properly
Confirm the display is on the input the device is actually plugged into. On a receiver, confirm it is passing that input through rather than sitting on another.
2. Force a handshake
Power everything off, unplug the HDMI cable at both ends, power the display on, then the receiver, then the source, then reconnect. HDCP negotiation happens at connection, and it fails silently.
3. Bandwidth
Set the source to a lower resolution or refresh rate. If 1080p works and 4K at 120 Hz does not, the problem is bandwidth — which means the cable length or category, or an intermediate device rated lower than the ends.
4. The intermediate devices
A splitter, switch or extender in the chain has to support the same bandwidth and the same HDCP version as both ends. This is where a working system breaks after adding one small box.
5. Only then, the cable
And when you replace it, replace it with a shorter certified one rather than a longer expensive one. Length is the cause far more often than quality.
Questions people actually ask
Why does it work sometimes and not others?
That pattern points at bandwidth or a marginal cable rather than at a broken connection. An intermittent picture at 4K that is stable at 1080p is the classic signature, and a shorter certified cable is the usual fix.
Do I need to power things on in a particular order?
It should not matter and sometimes it does. Powering the display first, then the receiver, then the source gives the handshake the best chance, and a system that only works in one order is telling you something about one of its links.
Last reviewed 4 September 2026