I hope I'm right at least.
I have a D-Link DI-624+ router. I used these settings:
DDNS: Enabled
Server Adress:
http://dns.loopia.se/XDynDNSServer/XDynDNS.phpHost name: mydomain.se,myotherdomain.se
Username: mylogin
Password: mypassword
All according to the info I found in the Loopia manual pages. It's worked so far but I actually don't know if my IP has changed since I set it. It doesn't change very often.