Can you extend e-Visa Vietnam from Philippines?

As a rule, Vietnam Online Visa (Vietnam e-Visa) CANNOT be extended now. 

Vietnam e-Visa is launched as a single entry authorization. The e-Visa accepts the visa holders can stay for up to 30 days. Remember that Vietnam e-Visa is suitable for tourist purposes. Before applying for an e-Visa, you have to check the requirements and consider whether your demand is matched. If not, we suggest you apply for a regular visa at the Vietnam Embassy that is suitable for you. Once you arrive in Vietnam, you can extend your tourist visa.

Applying for a new Vietnam visa online is a simple and straightforward process. However, this Vietnam e-Visa is not extendable, cancellable, transferable, or amendable once issued. If you would like to come back to Vietnam, you have to apply for a revisit visa to enter Vietnam legally.