Unfortunately, all characteristics of Shadowsocks (SS) and ShadowsocksR (SSR) have been fully and absolutely identified and controlled by GFW ("thanks to" the forced compromise from their developers). In short, as long as the GFW wants to block your VPS, it can now do this easily and perfectly in less than 30 seconds. If you find that your SS/SSR is still working well, that means GFW has no interest or there is no need to ban you right now. Of course, each blocking cycle of GFW is about 10 weeks. Therefore, we can roughly calculate when our VPS can be unblocked.