Gui unavailable

Please follow the below template, it will help us to help you!

Output of pi@raspberrypi:~ $ sudo systemctl status lighttpd

● lighttpd.service - Lighttpd Daemon
Loaded: loaded (/lib/systemd/system/lighttpd.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Wed 2021-11-24 11:12:29 CET; 12min ago
Process: 2767 ExecStartPre=/usr/sbin/lighttpd -tt -f /etc/lighttpd/lighttpd.conf (code=exited, status=0/SUCCESS)
Process: 2774 ExecStart=/usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf (code=exited, status=255/EXCEPTION)
Main PID: 2774 (code=exited, status=255/EXCEPTION)

Nov 24 11:12:29 raspberrypi systemd[1]: lighttpd.service: Service RestartSec=100ms expired, scheduling restart.
Nov 24 11:12:29 raspberrypi systemd[1]: lighttpd.service: Scheduled restart job, restart counter is at 5.
Nov 24 11:12:29 raspberrypi systemd[1]: Stopped Lighttpd Daemon.
Nov 24 11:12:29 raspberrypi systemd[1]: lighttpd.service: Start request repeated too quickly.
Nov 24 11:12:29 raspberrypi systemd[1]: lighttpd.service: Failed with result 'exit-code'.
Nov 24 11:12:29 raspberrypi systemd[1]: Failed to start Lighttpd Daemon.

Expected Behaviour:

Gui available

Actual Behaviour:

Gui not available

Debug Token:

https://tricorder.pi-hole.net/f6DFAowF/

You are running another webserver besides Pi-hole's lighttpd on your RPi:

*** [ DIAGNOSING ]: Ports in use
[80] is in use by apache2 (https://docs.pi-hole.net/main/prerequisites/#ports)

You should configure one of them for a different port.
See e.g. Lighttpd daemon won't start - #11 by Bucking_Horn for a possible lighttpd configuration.

Thank you very much, there was a apache server running in parallel.
After disabling with sudo /etc/init.d/ apache2 stop GUI is up again.