My local network is handled using a wireless router flashed with DD-WRT. I have a wireless device on my local network whose web interface I've been exposing to the Internet via port forwarding. I setup a dynamic dns (DynDNS) entry for my local network and had been successfully routing both local and external traffic to the forwarded port via this dns name.
A recent upgrade of the router firmware broke this port forwarding. External networks can still use the dynamic dns name. Local clients using this dns name fail to route the internal device. Local traffic still routes via the local IP.