hi @ralphshep welcome to the forum 
your description is very confusing and hard to understand. Please focus on one issue at time e.g. WebDAV has nothing to do with SMB and the fact access via SMB works doesn’t provide any evidence regarding WebDAV. Please describe the problem in a way so somebody completely unfamiliar with you system can understand the setup.
Please use the search - lot of issues have been discussed already e.g. the error when accessing other system living on the same host is described here:
from what you posted I understand
- Photoprism can not access WebDAV shares
- but you still try to store file on WebDAV
- access to WebDAV is possible (or not)
- Nextcloud can not save the file to WebDAV share (how does is access this share)
Please clarify which system is doing what and what did you tried to analyze the issue.