diff --git a/doc/adding-a-device.md b/doc/adding-a-device.md
index 0063dd71..8d45d198 100644
--- a/doc/adding-a-device.md
+++ b/doc/adding-a-device.md
@@ -177,3 +177,20 @@ Once the board has been tested on hardware:
    `doc/devices/KP-9000-6XH-X2.md` and document which `MACHINE` to pick for
    which silkscreen.
 
+### Identifying the CPU variant
+
+For RTL8373-based devices, use the read-only console command below to distinguish
+the N and non-N CPU variants:
+
+```text
+regget 4
+```
+
+| Register 0x0004 value | CPU |
+|---|---|
+| `0x83730000` | RTL8373 (non-N) |
+| `0x83737000` | RTL8373N |
+
+Record the identified CPU in the device documentation. These values identify
+only the CPU variant; document PHY and flash-chip models separately when verified.
+
diff --git a/doc/devices/SWTGW218AS.md b/doc/devices/SWTGW218AS.md
index 4797125b..485584f9 100644
--- a/doc/devices/SWTGW218AS.md
+++ b/doc/devices/SWTGW218AS.md
@@ -5,9 +5,15 @@
 |---|---|---|---|---|---|
 | Mokerlink | ZX-SWTGW218AS | Yes|  SWTG118AS-V2.0-16029 | 2MB (FM25Q16A)| 8273N + 8224N |
 | Sodola | | | | | |
-| Horaco | | | | | |
+| Horaco | HC-SWTGW218AS | Yes | SWTG118AS-V2.1 | 2MB | 8373 (non-N) |
 | XikeStor | SKS3200-8E1X | Yes | SWTG118AS-V2.1-17462 | 2MB (25Q16JVSIQ) | |
 
+All boards in this table use `MACHINE=SWTGW218AS`. The Horaco HC-SWTGW218AS is also sold with the
+[SWTG018AS-A V2.0](SWTG018AS_A_V2_0.md) board, which needs a different firmware. Check the marking
+on the PCB before flashing.
+
+The PHY and flash-chip models for the tested Horaco units remain unverified.
+
 
 ## Photos
 
diff --git a/doc/supported_devices.md b/doc/supported_devices.md
index ad113f7e..f87abd16 100644
--- a/doc/supported_devices.md
+++ b/doc/supported_devices.md
@@ -19,6 +19,7 @@ The following devices have been tested and are fully working:
 | hongyavision | LG-SG5T1    | No      | [PCB-SWTG024AS-V2.0_16895](devices/SWTG024AS-V2.0.md)                     | 0.5M  | 5 + 1 |
 | Horaco   | HC-SWTGW215AS   | Yes     | [SWTG024AS-A-V2.0.1_19650 5C 1SFP](devices/SWTG024AS-A-V2.0.1_5C_1SFP.md) | ?     | 5 + 1 |
 | Horaco   | HC-SWTGW218AS   | Yes     | [SWTG018AS-A V2.0](devices/SWTG018AS_A_V2_0.md)                           |       | 8 + 1 |
+| Horaco   | HC-SWTGW218AS   | Yes     | [SWTG118AS-V2.1](devices/SWTGW218AS.md)                                   | 2M    | 8 + 1 |
 | Horaco   | ZX310S-4T2XH    | Yes     | [PCB-SL310S-4T1T1X-V1.0.1-24107](devices/ZX310S-4T2XH.md)                 | 2M    | 5 + 1 |
 | Horaco   | ZX310S-4T2XT    | Yes     | [PCB-SL310S-4T2XT-V1.0.0-22273](devices/ZX310S-4T2XT.md)                  | 2M    | 6     |
 | Horaco   | ZX-SG4T2        | No      | [SWTG024AS-A-V2.0.1_19650_4C_2SFP](devices/SWTG024AS-A-V2.0.1_4C_2SFP.md) | 0.5M  | 4 + 2 |