wifi 24/7... or shared office space (Ho Chi Minh City)

hello,

I'll move to Saigon in April and found a house to stay, but there's no wifi. I really need to work on my jobs based in Hong Kong, and I work at random hours, so places like Starbucks are not suitable. It should be a wireless that is reliable and fast as I sometimes need to upload huge graphic or video files.
I'm thinking of using these 3G usb keys, have you tried them in Saigon?
Taking a subscription can be possible, depending on the minimum period. Not sure how long I will/can stay in Vietnam, but at least 3 months.

Another possibility is that I share an office space, if it is accessible 24/7. I'm a freelance designer for events, so the working hours vary.

Please let me know,
thanks & have a good day!

Tuan