psono server offline

Hello, I installed the server as described in the documentation. I use a reverseproxy to connect to the web client and the web client use the internal hostname to connect to the server. I already verified that I can reach the server from the web client:

docker exec -ti psono-webclient /bin/sh
/ # curl psono-server
{"detail":"Authentication credentials were not provided."}

In the psono server settings.yml the following parameters are set:

ALLOWED_HOSTS: ['*']
ALLOWED_DOMAINS: ['*']

When I try to login or register, I get the error message that the server is offline. Can anybody help?

The psono startup log:

*** Starting uWSGI 2.0.17.1 (64bit) on [Thu Sep 20 11:02:53 2018] ***
compiled with version: 6.3.0 on 09 September 2018 08:43:16
os: Linux-4.9.0-7-amd64 #1 SMP Debian 4.9.110-3+deb9u2 (2018-08-13)
nodename: psono-server
machine: x86_64
clock source: unix
detected number of CPU cores: 8
current working directory: /root
detected binary path: /usr/local/bin/uwsgi
!!! no internal routing support, rebuild with pcre support !!!
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) *** 
chdir() to /root/psono
your memory page size is 4096 bytes
detected max file descriptor number: 1048576
lock engine: pthread robust mutexes
thunder lock: disabled (you can enable it with --thunder-lock)
uwsgi socket 0 bound to TCP address :80 fd 3
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) *** 
Python version: 3.6.6 (default, Jun 27 2018, 22:45:12)  [GCC 6.3.0]
*** Python threads support is disabled. You can enable it with --enable-threads ***
Python main interpreter initialized at 0x558626b0d7a0
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) *** 
your server socket listen backlog is limited to 100 connections
your mercy for graceful operations on workers is 60 seconds
mapped 802120 bytes (783 KB) for 10 cores
*** Operational MODE: preforking ***
WSGI app 0 (mountpoint='') ready in 1 seconds on interpreter 0x558626b0d7a0 pid: 13 (default app)
uWSGI running as root, you can use --uid/--gid/--chroot options
*** WARNING: you are running uWSGI as root !!! (use the --uid flag) *** 
*** uWSGI is running in multiple interpreter mode ***
spawned uWSGI master process (pid: 13)
spawned uWSGI worker 1 (pid: 18, cores: 1)
spawned uWSGI worker 2 (pid: 19, cores: 1)
spawned uWSGI worker 3 (pid: 20, cores: 1)
spawned uWSGI worker 4 (pid: 21, cores: 1)
spawned uWSGI worker 5 (pid: 22, cores: 1)
spawned uWSGI worker 6 (pid: 23, cores: 1)
spawned uWSGI worker 7 (pid: 24, cores: 1)
spawned uWSGI worker 8 (pid: 25, cores: 1)
spawned uWSGI worker 9 (pid: 26, cores: 1)
spawned uWSGI worker 10 (pid: 27, cores: 1)