diff --git a/README.md b/README.md
index 192908c..8748ddc 100644
--- a/README.md
+++ b/README.md
@@ -75,8 +75,9 @@ sudo cp packaging/linux/70-benchpod.rules /etc/udev/rules.d/
 sudo udevadm control --reload-rules && sudo udevadm trigger
 ```
 
-It sets `ENV{ID_MM_DEVICE_IGNORE}="1"` for the pod's USB IDs: `1209:0001` (firmware
-3.9.0 and later) and `0483:5740` (older firmware), and `TAG+="uaccess"`, which lets the
+It sets `ENV{ID_MM_DEVICE_IGNORE}="1"` for the pod's USB IDs: `0483:5740` (ST's stock CDC
+ID, every STM32 firmware including 3.9.0; it also matches other ST CDC devices) and
+`1209:0001` (pre-release 3.9.0 builds), and `TAG+="uaccess"`, which lets the
 user signed in at the desktop open the console without joining the `dialout` group. Over
 SSH, or without the rule, add yourself to `dialout` (`sudo usermod -aG dialout $USER`,
 then log in again). On firmware 3.9.0 and later the network commands need neither: over
@@ -152,6 +153,12 @@ The USB network adapter works with the in-box drivers of macOS, Linux and Window
 (tested). Windows 10 (1903 or newer) is supported but not tested: if the adapter shows
 up without a driver there, open Device Manager, update its driver, and pick "UsbNcm
 Host Device" from the list of network adapters.
+The pod keeps ST's USB ID `0483:5740`: on a Windows computer with ST's Virtual COM Port
+driver installed, that driver can claim the whole pod, which then shows up as one COM
+port without the network adapter. Uninstall it for the pod (Device Manager, Ports,
+"STMicroelectronics Virtual COM Port", Uninstall device, tick "Attempt to remove the
+driver", then replug the pod); the steps are in the firmware's
+[USB serial interface](https://github.com/embeddedci-com/benchpod-firmware/blob/main/docs/usb-serial-interface.md) docs.
 WSL2 and Docker on Windows are not tested: Windows routes the pod's `10.237.x.y` address
 itself, so a WSL2 distribution or a container on the host network should reach it with
 `--connection <that address>`, but USB auto-detect and mDNS may not work from inside them.
diff --git a/cmd/benchpod-cli/flash_self.go b/cmd/benchpod-cli/flash_self.go
index 8a3c40e..ea83f62 100644
--- a/cmd/benchpod-cli/flash_self.go
+++ b/cmd/benchpod-cli/flash_self.go
@@ -385,7 +385,7 @@ func enterDfuViaConsole(g *globalFlags) error {
 	if err != nil {
 		return fmt.Errorf("enter-dfu: open USB console: %w", err)
 	}
-	// The USB serial number finds this pod again after the update, under its new USB ID.
+	// The USB serial number finds this pod again after the update, whatever its port is called then.
 	flashedPodSerial = serialconsole.PortSerialNumber(path)
 	defer cancel()
 	defer console.Close()
@@ -497,14 +497,14 @@ var flashedPodSerial string
 // Seams for tests: how long installBlobsAfterFlash waits for the flashed pod's USB console,
 // how often it tries, and how it opens it.
 var (
-	// Generous: from 3.8.x to 3.9.0 the pod comes back under a new USB ID, and Windows installs
-	// drivers and assigns a new COM port before the console appears.
+	// Generous: from 3.8.x to 3.9.0 the pod comes back as a composite device (console + network
+	// adapter), and Windows installs drivers and may assign a new COM port before the console appears.
 	flashedConsoleWait  = 150 * time.Second
 	flashedConsoleRetry = time.Second
 	openFlashedConsole  = func(g *globalFlags) (*serialconsole.Console, error) {
 		device := g.serialDevice()
 		if flashedPodSerial != "" {
-			// The same pod, whatever its port is called now (0483:5740 -> 1209:xxxx renames it).
+			// The same pod, whatever its port is called now (a new COM port on Windows, for one).
 			device = serialconsole.FindPodPortBySerial(flashedPodSerial)
 			if device == "" {
 				return nil, fmt.Errorf("the pod (USB serial number %s) is not back on USB yet", flashedPodSerial)
@@ -523,7 +523,7 @@ var (
 // versions as it came back and the blobs it installed (for the firmware report).
 func installBlobsAfterFlash(g *globalFlags, src blobSource) (after podVersions, installed []blobEntry, err error) {
 	fmt.Fprintln(os.Stderr, "flash-self: waiting for the pod's USB console to install its blobs (after an update to 3.9.0 "+
-		"it comes back under a new USB ID: Windows gives it a new COM port and may install drivers first)...")
+		"Windows may install drivers for its new network adapter and give it a new COM port first)...")
 	var console *serialconsole.Console
 	deadline := time.Now().Add(flashedConsoleWait)
 	for {
diff --git a/internal/serialconsole/portsn.go b/internal/serialconsole/portsn.go
index 2b286e4..6f32be6 100644
--- a/internal/serialconsole/portsn.go
+++ b/internal/serialconsole/portsn.go
@@ -6,8 +6,8 @@ import (
 )
 
 // The pod's USB serial number (12 hex digits from the MCU's unique ID) is the same on every
-// firmware, while its USB ID is not (0483:5740 up to 3.8, 1209:xxxx from 3.9.0) and the console's
-// port name may change with it (a new COM port number on Windows). After a firmware update the
+// firmware, while the console's port name may change (a new COM port number on Windows when 3.9.0
+// adds the network adapter; pre-release 3.9.0 builds also had another USB ID, 1209:0001). After a firmware update the
 // serial number is how the same pod is found again.
 
 // PortSerialNumber is the USB serial number of the port at path ("" when the enumerator does not
diff --git a/internal/serialconsole/serialconsole.go b/internal/serialconsole/serialconsole.go
index 8da34cc..04fd22d 100644
--- a/internal/serialconsole/serialconsole.go
+++ b/internal/serialconsole/serialconsole.go
@@ -34,8 +34,9 @@ import (
 //	2E8A — Raspberry Pi, the RP2350 pod's native USB port.
 //	0483 — STMicroelectronics, the STM32H563 pod up to firmware 3.8 (ST's
 //	       stock CDC VID/PID 0483:5740, so the host binds its in-box CDC driver).
-//	1209 — pid.codes, the STM32H563 pod from firmware 3.9.0 (1209:0001): a
-//	       composite device with the console and a USB network adapter.
+//	1209 — pid.codes, pre-release builds of firmware 3.9.0 (test ID 1209:0001). Released
+//	       3.9.0 keeps 0483:5740 (a composite device with the console and a USB network
+//	       adapter); the pod's own pid.codes ID 1209:EC10 is for a later release.
 //
 // None of the IDs is exclusive to a bench pod — 2E8A is shared with the CMSIS-DAP
 // probe's CDC, 0483:5740 with every ST Virtual COM Port on the bench and 1209
diff --git a/packaging/linux/70-benchpod.rules b/packaging/linux/70-benchpod.rules
index 0cb5815..b55c106 100644
--- a/packaging/linux/70-benchpod.rules
+++ b/packaging/linux/70-benchpod.rules
@@ -1,7 +1,7 @@
 # BenchPod: keep ModemManager off the pod's USB console, and let the signed-in desktop user open it
 # (uaccess) without joining the dialout group.
 # Install: sudo cp 70-benchpod.rules /etc/udev/rules.d/ && sudo udevadm control --reload-rules && sudo udevadm trigger
-# Firmware 3.9.0 and later (pid.codes VID 1209; PID 0001 is the test ID until ours is assigned).
-ATTRS{idVendor}=="1209", ATTRS{idProduct}=="0001", ENV{ID_MM_DEVICE_IGNORE}="1", TAG+="uaccess"
-# Older firmware (ST's stock CDC ID).
+# Every STM32 firmware, 3.9.0 included: ST's stock CDC ID.
 ATTRS{idVendor}=="0483", ATTRS{idProduct}=="5740", ENV{ID_MM_DEVICE_IGNORE}="1", TAG+="uaccess"
+# Pre-release 3.9.0 builds (pid.codes test ID).
+ATTRS{idVendor}=="1209", ATTRS{idProduct}=="0001", ENV{ID_MM_DEVICE_IGNORE}="1", TAG+="uaccess"