Cannot access website running on Apache2 server

I have an Apache2 server on Ubuntu 20.04 running a website on 192.168.0.20. So I tried wget 192.168.0.20 on another machine with ip address 192.168.0.19 which worked fine.

My problem is that I can't open 192.168.0.20 on my Firefox browser. It says Unable to connect, so I want to understand how to fix the problem.

By the way, I can open the website on my smartphone using Firefox.

I use the default apache2 configuration for the website.

Here are some logs.

/var/log/apache2/error.log - https://paste.ubuntu.com/p/gpW5dkxnst/

[Sat Nov 21 09:13:32.644472 2020] [mpm_event:notice] [pid 3100:tid 140282887253056] AH00489: Apache/2.4.41 (Ubuntu) configured -- resuming normal operations
[Sat Nov 21 09:13:32.646055 2020] [core:notice] [pid 3100:tid 140282887253056] AH00094: Command line: '/usr/sbin/apache2'
[Sat Nov 21 09:13:54.947877 2020] [mpm_event:notice] [pid 3100:tid 140282887253056] AH00491: caught SIGTERM, shutting down
[Sat Nov 21 09:13:55.061511 2020] [mpm_event:notice] [pid 3653:tid 140244737051712] AH00489: Apache/2.4.41 (Ubuntu) configured -- resuming normal operations
[Sat Nov 21 09:13:55.061714 2020] [core:notice] [pid 3653:tid 140244737051712] AH00094: Command line: '/usr/sbin/apache2'
[Sat Nov 21 09:20:09.047245 2020] [mpm_event:notice] [pid 3653:tid 140244737051712] AH00491: caught SIGTERM, shutting down
[Sat Nov 21 09:20:09.150602 2020] [mpm_event:notice] [pid 3781:tid 140160394517568] AH00489: Apache/2.4.41 (Ubuntu) configured -- resuming normal operations
[Sat Nov 21 09:20:09.150821 2020] [core:notice] [pid 3781:tid 140160394517568] AH00094: Command line: '/usr/sbin/apache2'
[Sat Nov 21 09:21:40.245009 2020] [mpm_event:notice] [pid 3781:tid 140160394517568] AH00491: caught SIGTERM, shutting down
[Sat Nov 21 09:21:50.559929 2020] [mpm_event:notice] [pid 4199:tid 139707575667776] AH00489: Apache/2.4.41 (Ubuntu) configured -- resuming normal operations
[Sat Nov 21 09:21:50.560142 2020] [core:notice] [pid 4199:tid 139707575667776] AH00094: Command line: '/usr/sbin/apache2'

/var/log/apache2/access.log - https://paste.ubuntu.com/p/twKhBf5w5w/

192.168.0.19 - - [21/Nov/2020:09:14:20 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:14:20 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Lin
ux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:14:21 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; 
rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:15:55 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:15:55 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:15:56 +0000] "GET / HTTP/1.1" 200 3476 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:15:56 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:16:33 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:16:33 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:17:30 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:17:30 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:17:31 +0000] "GET / HTTP/1.1" 200 3476 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:17:31 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:17:46 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko
) Chrome/87.0.4280.66 Safari/537.36"
192.168.0.19 - - [21/Nov/2020:09:17:47 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (X11; Linux x86_6
4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36"
192.168.0.19 - - [21/Nov/2020:09:17:47 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Linux x86_64) AppleWeb
Kit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36"
192.168.0.19 - - [21/Nov/2020:09:18:45 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.19 - - [21/Nov/2020:09:18:45 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linu
x x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:19:38 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firef
ox/83.0"
192.168.0.20 - - [21/Nov/2020:09:20:44 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:09:21:09 +0000] "GET /manual HTTP/1.0" 404 454 "http://192.168.0.20/" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:09:21:30 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:09:21:51 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
185.30.166.34 - - [21/Nov/2020:09:23:12 +0000] "CONNECT 85.94.204.153:31204 HTTP/1.0" 405 525 "-" "-"
185.30.166.34 - - [21/Nov/2020:09:23:12 +0000] "GET http://spamcheck.freenode.net/freenode-proxy-checker.txt HTTP/1.0" 404 464 "-" "-"
185.30.166.34 - - [21/Nov/2020:09:23:12 +0000] "POST http://spamcheck.freenode.net/freenode-proxy-checker.txt HTTP/1.0" 404 464 "-" "-"
185.30.166.34 - - [21/Nov/2020:09:23:12 +0000] "CONNECT 85.94.204.153:31204 HTTP/1.0" 405 525 "-" "-"
185.30.166.34 - - [21/Nov/2020:09:23:12 +0000] "GET / HTTP/1.1" 200 11173 "-" "-"
192.168.0.20 - - [21/Nov/2020:09:23:37 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.19 - - [21/Nov/2020:09:24:05 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
162.243.128.9 - - [21/Nov/2020:09:25:23 +0000] "GET /hudson HTTP/1.1" 404 436 "-" "Mozilla/5.0 zgrab/0.x"
192.168.0.19 - - [21/Nov/2020:09:28:58 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:28:59 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 304 180 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:34:23 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:34:24 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:36:47 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:39:15 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:39:15 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:47:44 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:47:44 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.20 - - [21/Nov/2020:09:48:15 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.19 - - [21/Nov/2020:09:49:12 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:49:12 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.19 - - [21/Nov/2020:09:49:13 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.20 - - [21/Nov/2020:09:49:18 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.18 - - [21/Nov/2020:09:49:25 +0000] "GET / HTTP/1.0" 200 3440 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.18 - - [21/Nov/2020:09:51:37 +0000] "GET / HTTP/1.1" 200 3477 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.18 - - [21/Nov/2020:09:51:37 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.18 - - [21/Nov/2020:09:51:37 +0000] "GET /favicon.ico HTTP/1.1" 404 490 "http://192.168.0.20/" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:83.0) Gecko/20100101 Firefox/83.0"
192.168.0.18 - - [21/Nov/2020:09:52:50 +0000] "GET / HTTP/1.0" 200 3452 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.18 - - [21/Nov/2020:09:54:19 +0000] "GET / HTTP/1.0" 200 3452 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:09:58:47 +0000] "GET / HTTP/1.0" 200 3452 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:09:58:50 +0000] "GET / HTTP/1.0" 200 3452 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"
192.168.0.20 - - [21/Nov/2020:10:01:05 +0000] "GET / HTTP/1.1" 200 11239 "-" "Wget/1.20.3 (linux-gnu)"
192.168.0.18 - - [21/Nov/2020:10:01:27 +0000] "GET / HTTP/1.1" 200 11239 "-" "Wget/1.20.3 (linux-gnu)"
192.168.0.14 - - [21/Nov/2020:10:12:41 +0000] "GET / HTTP/1.1" 200 3489 "-" "Mozilla/5.0 (Android 10; Mobile; rv:81.0) Gecko/81.0 Firefox/81.0"
192.168.0.14 - - [21/Nov/2020:10:12:41 +0000] "GET / HTTP/1.1" 200 3488 "-" "Mozilla/5.0 (Android 10; Mobile; rv:81.0) Gecko/81.0 Firefox/81.0"
192.168.0.14 - - [21/Nov/2020:10:12:41 +0000] "GET /icons/ubuntu-logo.png HTTP/1.1" 200 3623 "http://192.168.0.20/" "Mozilla/5.0 (Android 10; Mobile; rv:81.0) Gecko/81.0 Firefox/81.0"
192.168.0.18 - - [21/Nov/2020:10:14:59 +0000] "GET / HTTP/1.0" 200 3452 "-" "Lynx/2.9.0dev.5 libwww-FM/2.14 SSL-MM/1.4.1 GNUTLS/3.6.13"

ss -tulpen | grep '80\|443'

tcp LISTEN 0 511 *:80 *:* ino:45160 sk:6 v6only:0 <->