The given hostname does not exist in the config : errors during installation

After purging

I re-installed Jitsi-Meet in Ubuntu 18.04.4 Desktop, but got this error:

(base) marco@pc:~$ sudo apt install jitsi-meet
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  jicofo jitsi-meet-prosody jitsi-meet-turnserver jitsi-meet-web
  jitsi-meet-web-config jitsi-videobridge2
The following NEW packages will be installed:
  jicofo jitsi-meet jitsi-meet-prosody jitsi-meet-turnserver jitsi-meet-web
  jitsi-meet-web-config jitsi-videobridge2
0 upgraded, 7 newly installed, 0 to remove and 2 not upgraded.
Need to get 64,4 MB of archives.
After this operation, 106 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 https://download.jitsi.org stable/ jitsi-videobridge2 2.1-478-gc6da57bd-1 [33,4 MB]
Get:2 https://download.jitsi.org stable/ jicofo 1.0-740-1 [21,7 MB]                                                                                                                                        
Get:3 https://download.jitsi.org stable/ jitsi-meet-web 1.0.4900-1 [9.139 kB]                                                                                                                              
Get:4 https://download.jitsi.org stable/ jitsi-meet-web-config 1.0.4900-1 [18,8 kB]                                                                                                                        
Get:5 https://download.jitsi.org stable/ jitsi-meet-prosody 1.0.4900-1 [45,3 kB]                                                                                                                           
Get:6 https://download.jitsi.org stable/ jitsi-meet 2.0.5765-1 [3.344 B]                                                                                                                                   
Get:7 https://download.jitsi.org stable/ jitsi-meet-turnserver 1.0.4900-1 [6.248 B]                                                                                                                        
Fetched 64,4 MB in 19s (3.393 kB/s)                                                                                                                                                                        
Preconfiguring packages ...
Selecting previously unselected package jitsi-videobridge2.
(Reading database ... 396429 files and directories currently installed.)
Preparing to unpack .../jitsi-videobridge2_2.1-478-gc6da57bd-1_all.deb ...
Unpacking jitsi-videobridge2 (2.1-478-gc6da57bd-1) ...
Selecting previously unselected package jicofo.
Preparing to unpack .../jicofo_1.0-740-1_all.deb ...
Unpacking jicofo (1.0-740-1) ...
Selecting previously unselected package jitsi-meet-web.
Preparing to unpack .../jitsi-meet-web_1.0.4900-1_all.deb ...
Unpacking jitsi-meet-web (1.0.4900-1) ...
Selecting previously unselected package jitsi-meet-web-config.
Preparing to unpack .../jitsi-meet-web-config_1.0.4900-1_all.deb ...
Unpacking jitsi-meet-web-config (1.0.4900-1) ...
Selecting previously unselected package jitsi-meet-prosody.
Preparing to unpack .../jitsi-meet-prosody_1.0.4900-1_all.deb ...
Unpacking jitsi-meet-prosody (1.0.4900-1) ...
Setting up jitsi-videobridge2 (2.1-478-gc6da57bd-1) ...
Generating an empty hocon config
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
* Applying /etc/sysctl.d/10-console-messages.conf ...
kernel.printk = 4 4 1 7
* Applying /etc/sysctl.d/10-ipv6-privacy.conf ...
net.ipv6.conf.all.use_tempaddr = 2
net.ipv6.conf.default.use_tempaddr = 2
* Applying /etc/sysctl.d/10-kernel-hardening.conf ...
kernel.kptr_restrict = 1
* Applying /etc/sysctl.d/10-link-restrictions.conf ...
fs.protected_hardlinks = 1
fs.protected_symlinks = 1
* Applying /etc/sysctl.d/10-magic-sysrq.conf ...
kernel.sysrq = 176
* Applying /etc/sysctl.d/10-network-security.conf ...
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.all.rp_filter = 1
net.ipv4.tcp_syncookies = 1
* Applying /etc/sysctl.d/10-ptrace.conf ...
kernel.yama.ptrace_scope = 1
* Applying /etc/sysctl.d/10-zeropage.conf ...
vm.mmap_min_addr = 65536
* Applying /etc/sysctl.d/20-jvb-udp-buffers.conf ...
net.core.rmem_max = 10485760
net.core.netdev_max_backlog = 100000
* Applying /etc/sysctl.d/30-postgresql-shm.conf ...
* Applying /usr/lib/sysctl.d/50-default.conf ...
net.ipv4.conf.all.promote_secondaries = 1
net.core.default_qdisc = fq_codel
* Applying /etc/sysctl.d/99-sysctl.conf ...
fs.inotify.max_user_watches = 524288
fs.inotify.max_user_watches = 1048576
* Applying /etc/sysctl.conf ...
fs.inotify.max_user_watches = 524288
fs.inotify.max_user_watches = 1048576 
Created symlink /etc/systemd/system/multi-user.target.wants/jitsi-videobridge2.service → / 
lib/systemd/system/jitsi-videobridge2.service.
Selecting previously unselected package jitsi-meet.
(Reading database ... 397009 files and directories currently installed.)
Preparing to unpack .../jitsi-meet_2.0.5765-1_all.deb ...
Unpacking jitsi-meet (2.0.5765-1) ...
Setting up jitsi-meet-web-config (1.0.4900-1) ...
Can't load /home/marco/.rnd into RNG
140194101379520:error:2406F079:random number generator:RAND_load_file:Cannot open 
file:../crypto/rand/randfile.c:88:Filename=/home/marco/.rnd
Generating a RSA private key
...................................................................................++++
...................................................++++
writing new private key to '/etc/jitsi/meet/PC.key'
-----
----------------

You can now switch to a Let’s Encrypt certificate. To do so, execute:
/usr/share/jitsi-meet/scripts/install-letsencrypt-cert.sh

----------------
Selecting previously unselected package jitsi-meet-turnserver.
(Reading database ... 397012 files and directories currently installed.)
Preparing to unpack .../jitsi-meet-turnserver_1.0.4900-1_all.deb ...
Unpacking jitsi-meet-turnserver (1.0.4900-1) ...
Processing triggers for ureadahead (0.100.0-21) ...
ureadahead will be reprofiled on next reboot
Setting up jitsi-meet-web (1.0.4900-1) ...
Setting up jitsi-meet-prosody (1.0.4900-1) ...
net.server          error	libevent not found, falling back to select()
net.server          error	libevent not found, falling back to select()
Component "focus.PC" "client_proxy"
net.server          error	libevent not found, falling back to select()
The host 'focus.PC' is not configured for this server.
net.server          error	libevent not found, falling back to select()
The given hostname does not exist in the config
dpkg: error processing package jitsi-meet-prosody (--configure):
 installed jitsi-meet-prosody package post-installation script subprocess returned error exit status 1
Processing triggers for systemd (237-3ubuntu10.46) ...
Setting up jicofo (1.0-740-1) ...
Updating /etc/jitsi/jicofo/config to use jicofo.conf
Generating an empty jicofo.conf file
useradd: warning: the home directory already exists.
Not copying any file from skel directory into it.
dpkg: dependency problems prevent configuration of jitsi-meet:
 jitsi-meet depends on jitsi-meet-prosody (= 1.0.4900-1); however:
  Package jitsi-meet-prosody is not configured yet.

dpkg: error processing package jitsi-meet (--configure):
dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous     
failure.
                                                                                                          dpkg: dependency problems 
prevent configuration of jitsi-meet-turnserver:
 jitsi-meet-turnserver depends on jitsi-meet-prosody; however:
  Package jitsi-meet-prosody is not configured yet.

dpkg: error processing package jitsi-meet-turnserver (--configure):
 dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous 
failure.
                                                                                                          Processing triggers for systemd     
(237-3ubuntu10.46) ...
Processing triggers for ureadahead (0.100.0-21) ...
Errors were encountered while processing:
 jitsi-meet-prosody
 jitsi-meet
 jitsi-meet-turnserver
E: Sub-process /usr/bin/dpkg returned an error code (1)
(base) marco@pc:~$ 

What hostname should be given during installation for Jitsi Videobridge?

The DNS of your deployment, like meet.jit.si