Zabbix repository is unavailable with issues on both IPv6 and IPv4. From some locations it's been unaccessible for months, for others it's more of a general instability.

Here is an IPv4 & IPv6 test from Vultr New Jersey for example:

splitice@ny:~$ ping repo.zabbix.com
PING repo.zabbix.com (162.243.159.138) 56(84) bytes of data.
From repo.zabbix.com (162.243.159.138) icmp_seq=1 Destination Port Unreachable
From repo.zabbix.com (162.243.159.138) icmp_seq=2 Destination Port Unreachable
From repo.zabbix.com (162.243.159.138) icmp_seq=3 Destination Port Unreachable
^C
— repo.zabbix.com ping statistics —
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2003ms
splitice@ny:~$ curl repo.zabbix.com -v

• Rebuilt URL to: repo.zabbix.com/
• Hostname was NOT found in DNS cache
• Trying 2604:a880:1:20::b82:1001...
• connect to 2604:a880:1:20::b82:1001 port 80 failed: Connection refused
• Trying 162.243.159.138...
• connect to 162.243.159.138 port 80 failed: Connection refused