I'm guessing they have a blacklist of known VPN servers and block you from accessing them. One of the options is running a VPN server at your home outside of China.
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Ask your ISP to be excluded from their NAT and to give you a public IP address
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Use a DDNS service if your public IP changes regularly, so you have a domain name which always points to your current IP
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Install Wireguard VPN on your computer (or if you have a fancy router like Mikrotik run it on the router)
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Port forward a port to that computer/server
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Install Wireguard app on Android and connect. If done well, your data will be sent encrypted to your home, and you access the Internet from there.