The Elgato CamLink 4K needs the latest firmware to work reliably. Otherwise it is very sensitive to loose HDMI cables and can freeze up if the connection is poor. Fortunately there is a firmware update that fixes this problem. Unfortunately Elgato makes it hard to get, but here’s how.
Connect your CamLink 4K or other Elgato capture device to your computer via USB.
Run the 4K Capture Utility.
While holding the control key down, click the Preferences button in the upper-right corner (gear icon).
In the Preferences window, select the Device tab then choose Cam Link 4K from the drop-down menu.
If your firmware is less than “MCU: 20.02.19 / FPGA: 67” then you should upgrade. Click the Update Firmware button and follow the instructions.
Sometimes the update process ends with an error message saying the update failed. If that happens, follow the instructions to unplug the CamLink and plug it back in. Then run the update process again and it usually works the second time through.