I must check my ip first after connection with mobile ISP ( http://checkip.dyndns.com/ ) and then update the dyndns with my new ip http://username:password@members.dyndns.org/nic/update?hostname=yourhostname&myip=ipaddress&wildcard=NOCHG&mx=NOCHG&backmx=NOCHG . Port setup? Code for sketch?Thanks.