Some problem about openwrt firewall port forward

I've met some problem about openwrt firewall port forward.

Openwrt has a public ip address and worked as an openvpn server.
There is a plex server connected to openwrt through openvpn client and surfed the Internet normally(all traffic go through openvpn server) which behind nat.

plex server information:
local ip address:
openvpn client ip address:

openwrt information:
wan ip: x.x.x.x
br-lan ip address:
openvpn server ip address:

openwrt has an interface named rovpn belong to firewall zone rovpn.
Here is openwrt firewall zone setting.

Here comes the problem, I set up a firewall port forward rule: wan:32400 -> However it failed.

Suppose the wan interface address is A。
If I run ‘wget’ ,the output is ‘connected’.
No matter I am inside or outside the openwrt environment, the output of "wget A:32400" is always connetciton refused. :joy: :joy: :joy:
Uh, is there any way to figure out this issue?
Thank you all.