I removed an entry from Ysul defining matrix.nasqueron.org with a proxy_pass rule to http://matrix.nasqueron.org (sic).
My best guess is this has been done during the hsbxl talk on Matrix, as I used a chromebook without /etc/hosts editing capability to fix DNS.
If someone wants to play with https://matrix.org/ just pop a Docker image on Dwellers. If not, we can remove DNS entry.