Mwan3 2.0.3 can not co-exist with shadowsocks

I guess this issue is not that much LEDE related. But the new mwan3 2.0.3 which has a different approach compared with version 1.6.2, can not stay with a software so-called ShadowSocks (btw, shadowsocks is included by LEDE project) on Linux 4.x very well. In my country, I use ShadowSocks for anti-censorship and use mwan3 to fight with local ISP who intendedly limit the bandwidth of accessing abroad.

The issue is it takes quite a few seconds to open a site e.g. youtube.com which is thru ShadowSocks (without such a tool like ShadowSocks, in my country I can not open this site, nor for google, nor for facebook, nor for twitter etc and etc). However, this issue does not apply on mwan 1.6.2, which can co-exist with ShadowSocks on Linux 3.18 (that's OpenWrt CC) very well.