An adapter from a Kärcher (WD5 in my case) shop vac hose to the Dewalt DWS774 miter saw dust port.

A secure press fit to the miter saw and a weaker fit to the hose makes sure the hose won't fall out during use, while it is easy to remove the hose and keep the adapter in the miter saw.

Outer diameter on the miter saw side is tapered from 33 to 34.5 mm. Not sure if this might also fit other DeWalt miter saws.
Inner diameter on the shop vac side is tapered from 36 to 35 mm. I assume this is the same for all Kärcher shop vac hoses, and perhaps some other brands.