I have tried resetting my password but it still doesn't work, I have changed the case of the hostname, but still nothing. Error is attached.

My Config (Us3rN4me and Pa55word are not real but they represent the correct values :)

# ddclient configuration for Dynu
#
# /etc/ddclient.conf
daemon=60
syslog=yes
mail=root
mail-failure=root
pid=/var/run/ddclient.pid
use=web, web=checkip.dynu.com, web-skip='IP Address'
server=api.dynu.com
protocol=dyndns2
login=Us3rN4me
password='Pa55word'
njtsec.dynu.com

Are you using a dynu.com subdomain? As far as I know, only paid members can use dynu.com subdomains. If you are a free user, your hostname cannot be sth.dynu.com.

Garrrrrrrrrr, hostname problem

njtsec.dynu.com should be njtsec.dynu.net

Doh!!! :(

Thanks