Thanks for joining the NUC community.
I understand you have an Optoma beamer 3D capable but does not work with NUC DN2820FYKH.
I know the NUC integrates an Intel Celeron N2820 and when I checked specifications of the processor, I noticed that it does not have 3D features.
Did you test the Optoma beamer with another NUC model or PC?
Please check processor specifications here: ARK | Intel® Celeron® Processor N2820 (1M Cache, up to 2.39 GHz)