ip address from www.whatismyip.com and wanIP from modem are different

[guest1]

ip address from www.whatismyip.com and wanIP from modem are different

ip address i get from   www.whatismyip.com is:   209.121.228.zzz

and

if i log into my modem and go to  WANIP section, it's showing as  100.82.201.zzz

i need my own  external-ip/wan-ip

why is it different, need HELP

[Darren_P]

209.121.228.zzz is your external IP Address.

My WAN IP is the same as the result that I get from http://www.whatismyip.com/

I don't know why yours is different.