Disable IPv6 Autoconf with sysctl on Debian

I'm trying to setup IPv6 on my OVH server using their guide.

In the article they recommend to

disable IPv6 autoconf and router advertising to prevent known issues
You can do so by adding the following lines to your sysctl.conf file, which is located in /etc/sysctl.conf:
net.IPv6.conf.all.autoconf=0
net.IPv6.conf.all.accept_ra=0
Once this has been done, you can apply those rules by executing the following command: sh sysctl -p

I added those parameters to my the sysctl config like described. When trying to apply the config using sysctl -p I get the following error(s):

sysctl: cannot stat /proc/sys/net/IPv6/conf/all/autoconf: No such file or directory  
sysctl: cannot stat /proc/sys/net/IPv6/conf/all/accept_ra: No such file or directory

I'm on Debian 10 with a recent kernel:

# cat /proc/version
Linux version 4.19.0-9-amd64 (debian-kernel@lists.debian.org) (gcc version 8.3.0 (Debian 8.3.0-6)) #1 SMP Debian 4.19.118-2+deb10u1 (2020-06-07)
# cat /etc/os-release
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
NAME="Debian GNU/Linux"
VERSION_ID="10"
VERSION="10 (buster)"
VERSION_CODENAME=buster
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"