We arrive Hanoi Airport from Siem Rep

Hello, we arrive Hanoi airport from Siem rep and then depart Hanoi 2 .5 hours later to Hong Kong. However we are traveling on Vietnam airlines to Hong Kong and arrive on Cambodian airlines from Siem Rep. Two separate tickets. We need to collect our bags and check in again. Do we need a visa??

Dear Sir/Madam,
Thank you for contacting us!
Please be confirmed you that you do not need a Visa because you do not leave out of airport & make a clearance. After coming to Hanoi airport, please come directly to luggage counter & check in again. Vietnam does not require visa if you transit less than 24 hours.
For any other support, please do not hesitate to contact us!