Arch Linux

mariuszp

Member

Registered: 2026-02-06

Posts: 1

Getting an invalid default route on wlan0 no matter what I do

On my home network I have IPv4 connectivity only, and i've set up an arch linux machine with an IPv6-enabled VPN, which it routes through ethernet.

Everything almost works - except wlan0 is adding a default IPv6 route, even though there is no IPv6 connectivity through wlan0 (this is where IPv4 connectivity, including for the VPN, is coming from).

If i run "systemctl restart systemd-networkd", wlan0 gets only an IPv4 address, and no default IPv6 route. but after a few minutes, the IPv6 default route is re-added, i get link-local IPv6 addresses, and an IPv6 ULA.

The weird thing is i've done basically everything i can imagine to try to disable it. ip6tables is configured to DROP all INPUT, OUTPUT and FORWARD packets on wlan0. so there should be no way for RAs to even come through. Though blocking this should not even be necessary.

In /etc/systemd/network/19-wlan0.network I have:

[Match]
Name=wlan0

[Network]
DHCP=ipv4
IPv6AcceptRA=no
IPv6PrivacyExtensions=no
LinkLocalAddressing=ipv6
ConfigureWithoutCarrirer=yes

On top of this, i set some settings in /etc/sysctl.d/99-ipforward.conf:

net.ipv4.ip_forward=1
net.ipv6.conf.all.forwarding=1
net.ipv6.conf.wlan0.disabled_ipv6=1
net.ipv6.conf.wlan0.accept_ra_defrtr=0
net.ipv6.conf.wlan0.accept_ra=0
net.ipv6.conf.wlan0.autoconf=0

Yet no matter what, i get a default IPv6 on wlan0 on boot, and it only disappears for a few minutes after "systemctl restart systemd-networkd".

I'm very confused what's going on ,because it seems like it's just not respecting ANY of these settings.

What am i missing to just simply tell it: there is no IPv6 on wlan0, at the very least don't add a default route. This should be simple and all these settings should work, so I really don't understand what's causing that default route to appear.

This is a console-only arch linux, using only systemd-networkd (and iw for connecting to wifi).

Does anyone know what i could be missing here?

Thank you

seth

Member

From: Don't DM me only for attention

Registered: 2012-09-03

Posts: 72,938

Re: Getting an invalid default route on wlan0 no matter what I do

it only disappears for a few minutes after "systemctl restart systemd-networkd".

Sure there's nothing else configuring the routes, eg. you might have forgotten to disable dhcpcd or so?

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