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VPN's are used to help protect against malicious hackers and secure your devices. They are a standard piece of technology for most business, therefore I cant see StarHub deliberately trying to block VPN's. In most cases its the websites that want to prevent the use of VPN's, as the technology allows you to get around geo-restrictions on content (streaming etc). If you are having problems, i world suggest you speak with your VPN provider or check that your device hasn't been infected (as some malicious software tries to block the use of VPN's or can even be using its own VPN to tunnel your data via their servers).