I use Cloudflare for my machine's DNS. I wonder if there is an ancient cache in Cloudflare that only personal possession of drugs decriminalizing Oregonians hit?
Nonetheless:
% ping ploneconf.org
PING ploneconf.org (172.67.200.227): 56 data bytes
64 bytes from 172.67.200.227: icmp_seq=0 ttl=59 time=29.641 ms
64 bytes from 172.67.200.227: icmp_seq=1 ttl=59 time=25.102 ms
64 bytes from 172.67.200.227: icmp_seq=2 ttl=59 time=21.864 ms
% ping www.ploneconf.org
PING www.ploneconf.org (104.18.61.106): 56 data bytes
64 bytes from 104.18.61.106: icmp_seq=0 ttl=59 time=26.417 ms
64 bytes from 104.18.61.106: icmp_seq=1 ttl=59 time=22.241 ms
64 bytes from 104.18.61.106: icmp_seq=2 ttl=59 time=28.211 ms
% ping 2019.ploneconf.org
PING 2019.ploneconf.org (104.18.61.106): 56 data bytes
64 bytes from 104.18.61.106: icmp_seq=0 ttl=59 time=20.464 ms
64 bytes from 104.18.61.106: icmp_seq=1 ttl=59 time=23.740 ms
64 bytes from 104.18.61.106: icmp_seq=2 ttl=59 time=21.722 ms
% ping 2020.ploneconf.org
PING 2020.ploneconf.org (104.18.60.106): 56 data bytes
64 bytes from 104.18.60.106: icmp_seq=0 ttl=59 time=29.514 ms
64 bytes from 104.18.60.106: icmp_seq=1 ttl=59 time=27.104 ms
64 bytes from 104.18.60.106: icmp_seq=2 ttl=59 time=22.836 ms
Also interesting to note that www.ploneconf.org (with www.) does redirect to 2020.ploneconf.org. Something with a naked hostname is at issue. I'd check the DNS, then the server config.