The great firewall situation was always interesting, because if you would use a roaming Sim, then you will be able to access anything

Roaming SIMs work because the APN sets a network routing path outside of China.

Cool writeup. I remember implementing BBR many years ago when I was trying to bypass the Great Firewall for an extended stay. Helped deal greatly with the huge congestion on Chinanet backbone at the time, but it’s less of an issue these days now that foreigners can use CN2.