Submitted upstream: https://github.com/canonical/lightdm/pull/312

diff --git a/src/vnc-server.c b/src/vnc-server.c
index d3500764..00a2fc02 100644
--- a/src/vnc-server.c
+++ b/src/vnc-server.c
@@ -126,18 +126,10 @@ vnc_server_start (VNCServer *server)
 
     g_return_val_if_fail (server != NULL, FALSE);
 
-    g_autoptr(GError) ipv4_error = NULL;
-    priv->socket = open_tcp_socket (G_SOCKET_FAMILY_IPV4, priv->port, priv->listen_address, &ipv4_error);
-    if (ipv4_error)
-        g_warning ("Failed to create IPv4 VNC socket: %s", ipv4_error->message);
-
-    if (priv->socket)
-    {
-        GSource *source = g_socket_create_source (priv->socket, G_IO_IN, NULL);
-        g_source_set_callback (source, (GSourceFunc) read_cb, server, NULL);
-        g_source_attach (source, NULL);
-    }
-
+    // Bind to IPv6 first, as this implies binding to 0.0.0.0 in the
+    // Linux kernel default configuration, which would otherwise cause
+    // IPv6 clients to fail with "Error binding to address [::]:5900:
+    // Address already in use" (#266).
     g_autoptr(GError) ipv6_error = NULL;
     priv->socket6 = open_tcp_socket (G_SOCKET_FAMILY_IPV6, priv->port, priv->listen_address, &ipv6_error);
     if (ipv6_error)
@@ -150,6 +142,18 @@ vnc_server_start (VNCServer *server)
         g_source_attach (source, NULL);
     }
 
+    g_autoptr(GError) ipv4_error = NULL;
+    priv->socket = open_tcp_socket (G_SOCKET_FAMILY_IPV4, priv->port, priv->listen_address, &ipv4_error);
+    if (ipv4_error)
+        g_warning ("Failed to create IPv4 VNC socket: %s", ipv4_error->message);
+
+    if (priv->socket)
+    {
+        GSource *source = g_socket_create_source (priv->socket, G_IO_IN, NULL);
+        g_source_set_callback (source, (GSourceFunc) read_cb, server, NULL);
+        g_source_attach (source, NULL);
+    }
+
     if (!priv->socket && !priv->socket6)
         return FALSE;
 
>
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</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=6586c114e96585543e70e916902dd38b40d46c96'>root</a>/<a href='/guix/log/gnu?id=6586c114e96585543e70e916902dd38b40d46c96'>gnu</a>/<a href='/guix/log/gnu/installer?id=6586c114e96585543e70e916902dd38b40d46c96'>installer</a>/<a href='/guix/log/gnu/installer/user.scm?id=6586c114e96585543e70e916902dd38b40d46c96'>user.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/user.scm?id=6586c114e96585543e70e916902dd38b40d46c96&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-09-22 16:00:29 +0200'>2022-09-22</span></td><td><a href='/guix/commit/gnu/installer/user.scm?id=4814ec284f8a2870e6457c05f414ad31df4e3f57'>installer: Move &lt;secret&gt; to utils and use it for crypt passwords.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/user.scm (&lt;secret&gt;, secret?, make-secret, secret-content): Move
to utils.scm.
* gnu/installer/utils.scm (&lt;secret&gt;, secret?, make-secret, secret-content):
Moved from user.scm.
* gnu/installer/newt/partition.scm (prompt-luks-passwords): Make password a
&lt;secret&gt;.
* gnu/installer/parted.scm (luks-format-and-open): Unwrap secret.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>
<tr><td><span title='2022-08-08 11:54:25 +0200'>2022-08-08</span></td><td><a href='/guix/commit/gnu/installer/user.scm?id=ff9522fb69b9f4a31a5b766029e26dc53a2d1cf8'>installer: Add comments and vertical space to the generated config.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/parted.scm (user-partitions-&gt;configuration): Introduce
vertical space and a comment.
* gnu/installer/services.scm (G_): New macro.
(%system-services): Add comment for OpenSSH.
(system-services-&gt;configuration): Add vertical space and comments.
* gnu/installer/user.scm (users-&gt;configuration): Add comment.
* gnu/installer/steps.scm (format-configuration): Add comment.
(configuration-&gt;file): Expound leading comment.  Pass #:format-comment
to 'pretty-print-with-comments/splice'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-05-21 00:15:08 +0200'>2022-05-21</span></td><td><a href='/guix/commit/gnu/installer/user.scm?id=48c748226e2a94d2dec9bfdf84601455f00d6f5e'>Revert "installer: user: Remove useless filtering."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit c2125e59d0774cda3e559adeb056459a5f23586b.

Fixes &lt;https://issues.guix.gnu.org/55361&gt;.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-04-06 21:19:08 +0200'>2022-04-06</span></td><td><a href='/guix/commit/gnu/installer/user.scm?id=c2125e59d0774cda3e559adeb056459a5f23586b'>installer: user: Remove useless filtering.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/user.scm (users-&gt;configuration): Remove root account filtering
that is now performed in the "run-user-add-page" procedure.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2022-02-02 16:46:44 +0100'>2022-02-02</span></td><td><a href='/guix/commit/gnu/installer/user.scm?id=112ef30b84744872b3a7617d9e54b3df5db95560'>installer: Turn passwords into opaque records.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/user.scm (&lt;secret&gt;, secret?, make-secret,
secret-content): Add opaque &lt;secret&gt; record that boxes its contents,
with a custom printer that doesn't display anything.
* gnu/installer/newt/user.scm (run-user-add-page, run-user-page): Box
it.
* gnu/installer/final.scm (create-user-database): Unbox it.

Signed-off-by: Mathieu Othacehe &lt;othacehe@gnu.org&gt;
</span></span></td><td>Josselin Poiret</td></tr>