As a note, since some people are unaware/forget, please remember when using DynDNS to install and run the
DynDNS Update Client. The free dynamic DNS service has an automatic expiry of 30 days, and the update client (if kept running) will prevent it from expiring. It's incredibly tiny, takes almost no resources, and can simply be kept running as a background service on your computer. Once in a while it will poke DynDNS and basically say "Hey! I'm still using it! Don't expire!". Make sure to have the client running on the computer which is actually using the service, in this case your PC with the WOL capability.