There are several other people with similar issues, if you search the forum and github issues.
Have you tried to remove the wandevice thing and recreat it via gui → autodiscovery?
There are always two similar channels, e.g. wanIPAddress and wanPPPIPAddress. Only one will work depending on how your fritzbox is establishing a connection.
Yes, I searched the forum but did not find anything useful.
I used auto discovery and configured everything via the GUI.
The openHAB 3.2 installation is fresh. Installed it from scratch because the update from 3.1. did not work. So there should be no historic issue.
I am aware, that only one set of channels will work. In my case its the WANIPAddress that gets populated. All other items get NULL and the three above throw a warning message. I deleted the related items, but still get these messages.
Please purge any orphan link that still exists (or recreate the thing with a different id, as the orphan links will throw an error again if recreating with the same id)
From the karaf console:
Usage: openhab:links orphan - <list|purge> lists/purges all links with one missing element