Reflection does not work when Global Illumination on High

Hi again, sorry for being late. Firstly, I think that I need to use Lumen for realistic ambiance lighting. If I’m wrong please correct me. So, Lumen is first thing that I need to use for my archviz. Beside this, what is the best possible option to reflect my mirrors and glasses? If its not possible to see ‘‘best quality’’ how can I reach ‘‘average quality’’ with Lumen?

Btw, there is a video that enough for me either way for realistic view and mirror quality. Video owner in the comments says that he made the mirrors with Scenecapture2d but I couldn’t made that too. In this video I’m not sure that he made it with Lumen or not?