Problem DnyDNS and my router

Hi,

I have a Buffalo Airstation (WZR-RS-G54) and am using dynDNS. Two
problems occur:

1) As long as at least one PC behind the router is on, the automatic
DynDNS update works. BUT: I can remote manage the router by connecting
to its IP-address (in numbers), not using the DynDNS-address. (I can
remote connect to the PC using the DynDNS-address, though, so it gets
resolved correctly.)

2) When I turn all PCs behind the router, DynDNS updates stop, ebven
though they shouldn't. The router has a "wake up" feature for the PCs,
but I can't use it because I can't connect to thze router. Buffalo
says, the router should be able to do this, but it's not.

If anybody has any suggestions what to try next, I'd very much
appreciate it!

Thanks, Ulrich