How to setup VPN tunnel with dual VRT-311 installed behind the router?

Test network structure


Device A setting:
1.Configure Device A WAN IP to 210.66.155.90
2.Setup a virtual server to redirect IP protocol 50, IP protocol 51, UPD 500 and UDP 4500 from 210.66.155.90 to 192.168.2.253

VRT-311 setting:
1.Configure VRT-311 WAN IP address to 192.168.2.253
2.Configure VRT-311 VPN rule as the following image: