All I had to do on Debian 10 "Buster" and Debian 11 "Bullseye" was to open Outbound UDP Port 123
My inbound port 123 is not open.
Restarting any service isn't necessary.
Results in /var/log/syslog:
Sep 23 18:21:19 app systemd-timesyncd: Synchronized to time server for the first time 184.108.40.206:123 (0.debian.pool....
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 also had this problem, but the problem turned out to be a missing "ServerName" directive in the section. I suggest trying this modification to your configuration file:
# This parameter already existed as-is
# These are the parameters I changed (already existed w/ ...