こんなのも関係あるのかな
I managed to solve a similar problem by re-directing the checkip process to the same url with a different port.
inadyn defaults to using port 80 to check the ip.
This fails when I use the default DYNDNS settings because it checks my IP using checkip.dyndns.org.
Use the custom method to change this settings.

でも最初の一発が通るんだし何かねぇ