I haven't used this repo for awhile, but it works here, so does the webpage itself
01:09:57 PM-Wed Nov 21-[piper@x1] $ su
Password:
root@x1:/home/piper# apt update
Get:1 http://10.10.10.3:3142/incoming.debian.org/debian-buildd buildd-unstable InRelease [55.3 kB]
Hit:2 https://dl.winehq.org/wine-builds/debian sid InRelease
Hit:3 http://10.10.10.3:3142/mirror.math.princeton.edu/pub/debian unstable InRelease
Hit:4 http://10.10.10.3:3142/deb.debian.org/debian experimental InRelease
Hit:5 http://10.10.10.3:3142/mirror.math.princeton.edu/pub/siduction/extra unstable InRelease
Hit:6 http://10.10.10.3:3142/mirror.math.princeton.edu/pub/siduction/extra experimental InRelease
Hit:7 http://10.10.10.3:3142/packages.siduction.org/fixes unstable InRelease
Get:8 http://10.10.10.3:3142/www.deb-multimedia.org sid InRelease [24.2 kB]
Get:9 http://10.10.10.3:3142/incoming.debian.org/debian-buildd buildd-unstable/main Translation-en [175 kB]
Get:10 http://10.10.10.3:3142/www.deb-multimedia.org sid/main i386 Packages [156 kB]
Get:11 http://10.10.10.3:3142/www.deb-multimedia.org sid/main amd64 Packages [158 kB]
Get:12 http://10.10.10.3:3142/www.deb-multimedia.org sid/main Translation-en [57.3 kB]
Get:13 http://10.10.10.3:3142/www.deb-multimedia.org sid/main amd64 Contents (deb) [356 kB]
Get:14 http://10.10.10.3:3142/www.deb-multimedia.org sid/main i386 Contents (deb) [356 kB]
Get:15 http://10.10.10.3:3142/www.deb-multimedia.org sid/non-free i386 Packages [3,780 B]
Get:16 http://10.10.10.3:3142/www.deb-multimedia.org sid/non-free amd64 Packages [1,948 B]
Get:17 http://10.10.10.3:3142/www.deb-multimedia.org sid/non-free Translation-en [1,154 B]
Get:18 http://10.10.10.3:3142/www.deb-multimedia.org sid/non-free amd64 Contents (deb) [1,973 B]
Get:19 http://10.10.10.3:3142/www.deb-multimedia.org sid/non-free i386 Contents (deb) [4,104 B]
Fetched 1,350 kB in 5s (298 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
71 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@x1:/home/piper#