Strange incoming behaviour on port 80

I have installed my 5th droplet yesterday. I used Django on Nginx and Gunicorn (as usual). I also set up ufw according to DO tutorial.

As long as my site was up, I noticed strange incoming behaviour at port 80. This is a cut from the django’s log file I keep.

[01/Nov/2017 08:10:28] WARNING [django.request:152] Not Found: /abrhd/aovivonatv1/tracks-v2a1/index.m3u8
[01/Nov/2017 08:10:29] WARNING [django.request:152] Not Found: /abrhd/aovivonatv1/tracks-v2a1/index.m3u8
[01/Nov/2017 08:10:32] WARNING [django.request:152] Not Found: /abrhd/aovivonatv1/tracks-v2a1/index.m3u8
[01/Nov/2017 08:10:36] WARNING [django.request:152] Not Found: /abrhd/aovivonatv1/tracks-v2a1/index.m3u8
[01/Nov/2017 08:10:39] ERROR [django.security.DisallowedHost:80] Invalid HTTP_HOST header: 'extras.tv24.co'. You may need to add u'extras.tv24.co' to ALLOWED_HOSTS.
[01/Nov/2017 08:10:39] ERROR [django.security.DisallowedHost:80] Invalid HTTP_HOST header: 'extras.tv24.co'. You may need to add u'extras.tv24.co' to ALLOWED_HOSTS.
[01/Nov/2017 08:10:39] ERROR [django.security.DisallowedHost:80] Invalid HTTP_HOST header: 'extras.tv24.co'. You may need to add u'extras.tv24.co' to ALLOWED_HOSTS.

Whenever I disallow traffic to port 80 and allow to some other port (e.g. 88) I stop getting this kind of traffic. Strangely when I “ping extras.tv24.co” I get my Server’s IP.

What is going on?