In mid-January 2017, I will be moving to Viet Nam for two months for academic research. I will be staying in two cities: Hai Phong and Da Nang. Now, with the latter it has been relatively easy to find affordable accommodation. However, for Hai Phong I'm running into some serious difficulties. All I can find is hotels (which are $25+ a day which is too expensive for me) since the only cheap options are hostels on Cat Ba. However, I don't really want to live in Cat Ba since I would have to take the ferry every day to the main city. Does anybody have an idea where I could find affordable accommodation in Hai Phong for a period of ~3 weeks? My budget is a maximum of $450 per month (15$ per day) but preferably less. I do not seek an apartment but a single room with a bed, so I'm not looking for anything luxurious.
PS: In case anyone is aware of a Haiphong/Da Nang-based English-speaking Facebook group, I'd love to hear about that too.