PPP link performance (PPTP vs SSTP) across Chinese Internet broder

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Please take a look at the above diagram, it shows that there is a PPP link across two networks. One side is on the China mainland side and the other is on the Hong Kong side.

If the PPP link is formed by means of PPTP, the traffic speed is faster.
If the PPP link is formed by means of SSTP, the traffic speed is a bit slower than the above one.

For PPTP link, "they" can see the contents. If they find some websites are not allowed to see, then they will block them.
For SSTP link, "they" cannot see the contents. Depending on their system configuration, sometimes all the traffics are blocked.

As a result, which link should be used? PPTP link or SSTP link? It all depends on your choice, if you do not mind to allow them to see your data, then you should use PPTP link. However if it is not, you have to choose the latter one (SSTP).

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Even for the PPTP link, if the traffic is large (for internet speed test), then "their" system finds it. They will break the link. I guess that they would not like to spend to much time to see the contents due to heavy traffic. If the traffic is not large, for instance (I guess) medium sized packets, then it may allow them to go.