I'm seeting uo in DDWRT and am receiving the following in theService Status:

In-a-dyn version 2.10.0 -- Dynamic DNS update client.
Update forced for alias andersonserver.freeddns.org, new IP# 71.68.55.179
Fatal error in DDNS server response: DDNS server response not OK
Error response from DDNS server, ignoring ...

same here:

Fatal error in DDNS server response: Authentication failure
Error response from DDNS server, ignoring ...

But seems to be working.