FYI, VN will not through-check your luggage if the connection time between both flights is more than 4 hours.

As a result, you can be left sitting with your luggage in SGN (or in any other airport) public area, waiting for the counters to let you check in for your next flight (3 hours before departure).

Had I known this, I would have constructed my routing differently.

P.s. this rule does not apply to International connections (for example PER/SGN/CDG). under 24 hours.

In this case, one can through-check or choose to retrieve the luggage and recheck.