The Consulate General of Hungary in Ho Chi Minh City only represents Poland in the case of visa applications lasting no more than 90 days within any 180-day period.
The conditions for submitting the application are set out in Sections 1-5. can be found under menu items.
In addition to the above, please find information about the visa application procedure and supporting documents on the website of the Embassy of Poland in Hanoi.
Embassy of Poland: https://www.gov.pl/web/vietnam