I'm no expert, but looking up Vietnamese spiders, it could be a huntsman?
Disclaimer: I know nothing more than the average person on spiders, it may be harmful, it may not be a huntsman. I would advise caution until someone who knows more that I can identify it.
I'm pretty sure I've seen bigger! I'm okay with them usually, but they can make you uneasy. I had one living under my car bonnet for about a month in one occasion, the guy would come out at dusk and scare the shit out of me while driving. He would run all over the outside of the car and not fall, which is remarkable considering I did up to 70kms ph.