Those shopvac vacuums can be very cheap and bad engineered. The original hose connector is attached inside the hose the vacuum side. It has a so small opening. It blocks all the time. I designed a new connector in Freecad that attach outside the hose. No more blocking now. The second picture shows the original part first. Printed in PLA (for now) with a brim.
The author marked this model as their own original creation.