iMacs not working in Target Display Mode

[Tomsjotun]

Is there any other way to solve it?

Originally Posted by rboerner

'Target Display Mode' does NOT use DisplayLink technology. As a result, DisplayLink will not be able to assist you.

That said, Apple has very specific requirements in order for Target Display Mode to work as they describe here --> https://support.apple.com/en-us/HT204592

If that information doesn't help, I would suggest contacting Apple directly for assistance.