Just wrapped up 1 month in China, route was Hong Kong to a circuit of big cities including: Shenzhen, Wuhan, Chongqing. Mullvad worked great on default Wireguard settings, I found European servers worked best, North American and Asian ones were inconsistent and kept disconnecting. Use servers from ‘big’ European nations, I found Germany, Netherlands, Denmark, and UK worked especially well, while ‘smaller’ countries like Slovakia were less consistent/fast. I also found Oceania servers in Australia and especially NZ to work well.
Keep in mind your mileage may vary depending on your location in China, network security, even device info, so take info on servers lightly. Don’t be afraid to jump servers every so often if your connection starts to fritz out.
Mullvad is best in class for China no questions asked if you’re wondering, 5 euro for 5 devices and this many servers is unmatched. I was traveling with my sister and we had all of our devices connected all at once, it was as if the Great Firewall never existed lol