In addition to Matthew's comment suspecting internal nat redirect
iptables -vnL -t nat or nft list ruleset ip
perhaps you could directly inspect port 80. These are some of the ways to do that:
ss -4tlnp -o state LISTENING '( sport = :80 )'
do a verbose tcpdump
do a verbose portscan with nmap
or, be even more explicit when testing with curl, ie ...
I discovered my Web host was not allowing TLS communication over port 443. My host said, "We had an application group called web browsing set in the rule that apparently did not have every TLS protocol in the group that your website was set to support." Windows Firewall is disabled in favor of some separate firewall that is outside my control, ...
ISP blocking ports
ISPs these days block used ports and 80 is the HTTP one which is the most common used port and protocol.
If you want details for blocked ports, contact your ISP.
OS Firewall Issue
If you have configured your firewall rules correctly and it doesn't work, check your server's OS firewall rules. Also make sure that the OS rule is Inbound and ...