Pihole in docker together with nextlcoud and nginx

Ok, i choosed WEB_PORT=8081 (8080 is reserved). Still the same problem. My docker-compose.yml looks like this:

version: '3.1'

services:
  pihole:
    image: pihole/pihole:latest
    container_name: pihole
    restart: always
    volumes:
      - ./pihole/:/etc/pihole/
      - ./pihole/dnsmasq.d/:/etc/dnsmasq.d/
    ports:
      - '53:53/tcp'
      - '53:53/udp'
    environment:
      - ServerIP=192.168.178.28
      - PROXY_LOCATION=pihole
      - TZ=America/Chicago
      - WEB_PORT=8081
      - WEBPASSWORD=PIHOLEPW
    dns:
      - 127.0.0.1
      - 1.1.1.1
    cap_add:
      - NET_ADMIN
    restart: unless-stopped

This is the docker log:

[s6-init] making user provided files available at /var/run/s6/etc...exited 0.
[s6-init] ensuring user provided files have correct perms...exited 0.
[fix-attrs.d] applying ownership & permissions fixes...
[fix-attrs.d] 01-resolver-resolv: applying...
[fix-attrs.d] 01-resolver-resolv: exited 0.
[fix-attrs.d] done.
[cont-init.d] executing container initialization scripts...
[cont-init.d] 20-start.sh: executing...
 ::: Starting docker specific checks & setup for docker pihole/pihole
WARNING Misconfigured DNS in /etc/resolv.conf: Two DNS servers are recommended, 127.0.0.1 and any backup server
WARNING Misconfigured DNS in /etc/resolv.conf: Primary DNS should be 127.0.0.1 (found 127.0.0.11)

search fritz.box
nameserver 127.0.0.11
options ndots:0
  [✓] Update local cache of available packages
  [i] Existing PHP installation detected : PHP version 7.0.33-0+deb9u8

  [i] Installing configs from /etc/.pihole...
  [i] Existing dnsmasq.conf found... it is not a Pi-hole file, leaving alone!
  [✓] Copying 01-pihole.conf to /etc/dnsmasq.d/01-pihole.conf
chown: cannot access '': No such file or directory
chmod: cannot access '': No such file or directory
chown: cannot access '/etc/pihole/dhcp.leases': No such file or directory
Custom WEB_PORT set to 8081
INFO: Without proper router DNAT forwarding to 192.168.178.28:8081, you may not get any blocked websites on ads
Setting password: PIHOLEPW
+ pihole -a -p 'PIHOLEPW' 'PIHOLEPW'
  [✓] New password set
Using default DNS servers: 8.8.8.8 & 8.8.4.4
DNSMasq binding to default interface: eth0
Added ENV to php:
                        "PHP_ERROR_LOG" => "/var/log/lighttpd/error.log",
                        "ServerIP" => "192.168.178.28",
                        "VIRTUAL_HOST" => "192.168.178.28",
Using IPv4 and IPv6
::: setup_blocklists now setting default blocklists up:
::: TIP: Use a docker volume for /etc/pihole/adlists.list if you want to customize for first boot
::: Blocklists (/etc/pihole/adlists.list) now set to:
https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
https://mirror1.malwaredomains.com/files/justdomains
::: Testing pihole-FTL DNS: FTL started!
::: Testing lighttpd config: Syntax OK
::: All config checks passed, cleared for startup ...
 ::: Docker start setup complete
  [i] Creating new gravity database
  [i] Migrating content of /etc/pihole/adlists.list into new database
  [i] Neutrino emissions detected...
  [✓] Pulling blocklist source list into range

  [✓] Preparing new gravity database
  [i] Target: https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
  [✓] Status: Retrieval successful
  [i] Received 57660 domains

  [i] Target: https://mirror1.malwaredomains.com/files/justdomains
  [✓] Status: Retrieval successful
  [i] Received 26853 domains

  [✓] Storing downloaded domains in new gravity database
  [✓] Building tree
  [✓] Swapping databases
  [i] Number of gravity domains: 84513 (84470 unique domains)
  [i] Number of exact blacklisted domains: 0
  [i] Number of regex blacklist filters: 0
  [i] Number of exact whitelisted domains: 0
  [i] Number of regex whitelist filters: 0
  [✓] Cleaning up stray matter

  [✓] DNS service is running
  [i] Pi-hole blocking will be enabled
  [i] Enabling blocking
  [✓] Pi-hole Enabled
  Pi-hole version is v5.1.1 (Latest: v5.1.1)
  AdminLTE version is v5.1 (Latest: v5.1)
  FTL version is v5.1 (Latest: v5.1)
[cont-init.d] 20-start.sh: exited 0.
[cont-init.d] done.
[services.d] starting services
Starting pihole-FTL (no-daemon) as root
Starting lighttpd
Starting crond
[services.d] done.

Weird, i don't get this one:

WARNING Misconfigured DNS in /etc/resolv.conf: Two DNS servers are recommended, 127.0.0.1 and any backup server
WARNING Misconfigured DNS in /etc/resolv.conf: Primary DNS should be 127.0.0.1 (found 127.0.0.11)

Why 127.0.0.11? DNS is declared as 127.0.0.1. The rest looks okay to me.
I also tried my router ip 192.168.178.1. The output in the log is the same:

WARNING Misconfigured DNS in /etc/resolv.conf: Two DNS servers are recommended, 127.0.0.1 and any backup server
WARNING Misconfigured DNS in /etc/resolv.conf: Primary DNS should be 127.0.0.1 (found 127.0.0.11)

The pihole container is running (docker ps -a) but the port 8081 is not used:
sudo lsof -i -P -n | grep 8081
-> nothing. Docker is only using port 80 and 443 (nextcloud) and 53.

/var/log/lighthttpd/error.log just says:

2020-07-21 16:15:04: (log.c.217) server started

root@8b560484a12e:# cat /etc/resolv.conf
search fritz.box
nameserver 127.0.0.11
options ndots:0