If so, please post your ddclient.conf after removing any
passwords.
If ping works doesn't that suggest that ddclient is working?
No. It implied that dyndys has a mapping from your domain name
to an IP address which has a machine answering pings.
If your ISP has re-assigned the IP you were using, and someone
else is using it, then ping will work and your ssh will fail.
That's why I asked you to post your ddclient config, minus any
passwords.
#protocol=dyndns2
#use=if, if=eth0
#server=https:members.dyndns.org
#login=waterhorse
## ddclient configuration file
daemon=600
# check every 600 seconds
syslog=yes
# log update msgs to syslog
mail-failure=waterhorse@ultrasw.com # Mail failed updates to user
pid=/var/run/ddclient.pid
# record PID in file.
ssl=yes
# use HTTPS
## Detect IP with our CheckIP server
use=web, web=checkip.dyndns.com/, web-skip='IP Address'
## DynDNS username and password here
login=waterhorse
#password=##YOUR PASSWORD##
password='[password deleted]'
## Default options
protocol=dyndns2
server=members.dyndns.org
## Dynamic DNS hosts
waterhorse.dyndns.org