pfSense

Try this change, for example:

diff --git a/src/etc/rc.linkup b/src/etc/rc.linkup
index 1eb0f0e342..7c81e49a83 100755
--- a/src/etc/rc.linkup
+++ b/src/etc/rc.linkup
@@ -29,10 +29,6 @@ require_once("filter.inc");
 require_once("shaper.inc");
 require_once("interfaces.inc");

-if (platform_booting()) {
-       return;
-}
-
 function handle_argument_group($iface, $action) {
        global $g, $config;

@@ -162,6 +158,21 @@ if (!in_array($action, ['start', 'stop'])) {
                return;
 }

+if (platform_booting()) {
+       if (!empty($realiface) &&
+           (config_get_path("interfaces/{$realiface}/ipaddr", '') == 'dhcp')) {
+               if (find_dhclient_process($realiface) == 0) {
+                       /* dhclient is not running */
+                       $interface = convert_real_interface_to_friendly_interface_name($realiface);
+                       log_error("DHCP Client not running on {$interface} ($realiface) during boot, reconfiguring dhclient.");
+                       interface_dhcp_configure($interface);
+               }
+       } else {
+               log_error("Ignoring link event during boot sequence.");
+       }
+       return;
+}
+
 if (!empty($realiface)) {
        if (substr($realiface, 0, 4) == 'ovpn') {
                log_error("Ignoring link event for OpenVPN interface");

Untested, but sound in theory.

If that works I can check it in, but I'm hesitant to make that change without testing it first and I can't seem to trigger it here.

Updating subject for release notes.

Moving to the next release so we have more time to reproduce and test.

I was able to reproduce this in a VM finally. The key is to boot with the interface detected and then reconnect it just after the boot log shows the WAN configuration is finished.

The patch above doesn't fix it, but I have a commit coming that does.

Applied in changeset c37e9ab908cffe20227cc8c88ae5463b5562a397.

Tested on 23.01

I was able to reproduce this Bug on my KVM by turning WAN (DHCP) interface off at certain moment during boot process and then turning it on again after about 30-40 seconds but before boot process has finished. WAN got no IP via DHCP, I saw no DHCP requests coming out of WAN and WAN port stuck in 'no IP' state.
After applying the patch JimP mentioned in his last comment, WAN got IP-address in any cases.

I'll mark this Bug as Resolved.