Unable to upload files from Device to Server

I’m using seafile in a docker stack.
I commented out the line regarding port 443.
I want to sync my files/folders with folder sync pro over webdav. I’ve got the nginx proxy manager in front of my seafile container.
I’m accassing the seafile webui over the port 10000:80. Because if I try to use port 443 I only get a gateway timeout. But I have to use port 443 otherwise I get the error: "HTTP_BAD_GATEWAY, “Source and destination must have the same scheme.” Like the Issue 183 on mar10’s wsgidav github page.
How can I activate 443 in seafile?