This is a server that has all 65,535 ports open and responds to udp packets sent to any of those ports. For instance, you're currently connected to udp port 443 (the default https port):
The other ports don't have an https server listening to them, so you will not be able to visit them on your browser. However, you can use a tool like nmap instead:
nmap -sU -p- udpquiz.com
If the above command returns any status that's not "open", that probably means that a firewall on your network is blocking udp packets to that port. Exceptions: ports 67 and 1900 (blocked by my upstream provider) and port 443 (only responds to quic connections).
{{placeholder "udpquiz.bpf_packets"}} udp packets processed via eBPF since the last server restart on {{placeholder "udpquiz.start"}}.
Note that this site is only accessible via UDP. Source at GitHub.