The travel agency told me that the tourist visa to Vietnam was "refused without reason"

1. Generally speaking, group visas are only for tourists visiting North Vietnam. You need to send your passport to the consulate for visa before you can enter the country.

2. "No reason to refuse a visa" is generally the specific reason why the consulate did not apply for a visa for the travel agency. There are many reasons for the consulate to refuse a visa, such as your appearance and name are similar to those on their blacklist, or you have a bad record abroad, which will affect your visa application. It's normal to refuse a visa, so don't worry too much.