The DDNS URL works as I've used it to connect to my Synology remotely at work for example so good there.
The User does have read/write access, check.
Yes, your instructions were easy to follow (thank you) and I entered the credentials properly (and tested the credentials logging in remotely with the DS Video app on my phone).
I did need to authorize the user for webdav as that was not checked - done.
My router (only one) definitely has the functionality but I am just not technical enough to follow the on-screen prompts - there are some assumptions you know what your doing which I don't
However, I think I'm ok as I can get to the Synology with PC's and phones - just can't figure out how to create the link from Kodi.
I've only tried connecting from inside the house - I have not removed to try outside my LAN.
I have not tried connecting via the IP in webdav - is that using the external IP address of my Synology? I like the URL path as my IP address gets changed by Comcast and then I'd have to figure out how to update remotely which is way above my ability...
I will try and take another run at the user tonight using my Admin logon which has full read/write to all - that should identify if it is the username/pw/authorizations.
Thank you Miguix!