I upgraded to v3.0 firmware and followed the guide to enable the Shadowsocks client and it is working.
But I still have two problems:
The connection is very slow, even for normal web surfing. I noticed in the Advanced → Services → Shadowsocks → Transparent Proxy … the UDP-Relay Server shows “Unusable - Missing iptables-mod-tproxy”. I could not find this in the Applications - Plug-ins
DNS Leak test still show my DNS server as that of my ISP, not the VPN server’s. How do I prevent DNS leak.