"301 Permanently Moved" on nginx?

I'm trying to setup a grav website on a server (CentOS7, PHP7.0.11) using nginx.
I hat a site setup in XAMPP locally and everything worked fine.
But when I uploaded it to the server, I always got errors like "301 - PERMANENTLY MOVED" from nginx.
So I instead downloaded a new admin-plugin version and put it on the server without changing anythin.
This way I wanted to find out if it was my procect that was messed up or what else it might be.
The new site seems to work at least a little bit as it automatically redirects me to www.domain.com/admin/ but there I get another "301 - PERMANENTLY MOVED" error.
No entries in error log or grav log.
only nginx' access log tells me I tryed it acess www.domain.com/admin/ and got a 301... (not helpfull)
Can anyone help me? I'm running out of ideas here :(

*it's nginx/1.10.1 in case that's important :)

Did you use the sample configuration: webserver-configs/nginx.conf in the Grav download package?

I am now using this configuration for both [GRAV/webserver-configs/nginx.conf] and [/etc/nginx/nginx.conf]:
http://pastebin.com/qhFe8Yzd
Still I'm getting "file not found" an "moved permanently" errors everywhere... :(