I picked up these brass connectors a little while ago: https://www.amazon.com/gp/product/B087LQW92G/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 and seem to work fine with the bottle adapter (plastic), so I assume they work with the suction hose as it is the same plastic connector. I would try out the suction hose, but we're under restrictions, so I'm not allowed to wash my car at home which was the place I was using the washer.

I had picked up a number of the plastic ones, but the last time I used the washer, the plastic end in the washer snapped.

The brass connectors don't have the "stop when not connected" feature that the Melnor plastic ones had, however.