Cannot activate VPN if IPv6 disabled in the Kernel

[smutel]

Hello,

I disabled IPv6 in the Kernel by adding these lines in /etc/sysctl.conf:

net.ipv6.conf.all.disable_ipv6=1
net.ipv6.conf.default.disable_ipv6=1
net.ipv6.conf.lo.disable_ipv6=1

When I want to start wireguard VPN, the connection is failing and I have this error messages in syslog:

NetworkManager[7487]: [#] wg set wg0 fwmark 51820
NetworkManager[7487]: [#] ip -6 route add ::/0 dev wg0 table 51820
NetworkManager[7532]: Error: IPv6 is disabled on nexthop device.
NetworkManager[1766]: <info>  [1670406156.5651] device (wg0): state change: ip-check -> secondaries (reason 'none', sys-iface-state: 'external')
NetworkManager[1766]: <info>  [1670406156.5655] device (wg0): state change: secondaries -> activated (reason 'none', sys-iface-state: 'external')
NetworkManager[7487]: [#] ip link delete dev wg0

Here is the IPv6 configuration of wireguard in NetworkManager:

[ipv6]
addr-gen-mode=stable-privacy
dns-search=
ignore-auto-routes=true
ip6-privacy=0
method=disabled

Here is the IPv6 configuration of my network interface:

[ipv6]
addr-gen-mode=stable-privacy
dns-search=
ip6-privacy=0
method=disabled