As I already toldy by email, since you are located in Vietnam, you must use some kind of VPN service to access the update site, there's no way around, because we use a 3rd party service to shield us from malware and/spyware ( 95% of spam is coming from just 2-3 countries ), and they have those kind of settings at the server level we don't have much control on it.
But in any case, if you just download the current Stand-Alone Addon Manager for FSX, it will install the same things that are supposed to be get online, because it always kept updated to contain the latest online files internally, which means it will work and install the same stuff even without an internet connection.