There is no office of Vietnam embassy in Qatar up to now.
To request for legalization/verification of Vietnamese citizenship, etc., you have to contact the consulate or embassy of Vietnam in the nearest country to get detailed guidelines. You can find Vietnam embassy in the countries nearby Qatar here.
To request for a Vietnamese visa, consider two options below:
- Get a visa at the Vietnam embassy/consulate in the country close to Qatar;
- Get visa on arrival (VOA) at international airports of Vietnam
Vietnam visa on arrival is also known as visa at airport and highly recommended for air travelers to Vietnam from Qatar or any other country since it requires no contact with Vietnam embassy for application). See how Vietnam VOA works.