Letsencrypt permissions issue on NAS

Hi all

looking for some help, I know this is a permission issue but can’t figure it out.

My setup I have Docker running on a Synology NAS. I decided to try the LetsEncrypt docker image as this looks a good solution.

I have setup the image using my PUID and PGID taken from ID USERNAME on my NAS using ssh

Most things work fine, but 1 part of my website, a family tree software called web-trees is returning 500 errors when viewing images and logs the following “Cannot create thumbnail Unable to read image from path (tmp/RANDOMLETTERS)”

If I use Portainer and connect as the user abc (taken from the NGINX config file) navigate to the directory and run touch test.txt it creates the file and the permissions look correct. same with MKDIR command it creates a directory.

I can upload new files OK using web-trees but it’s unable to create the temp file for them.

Any ideas what could be wrong?