diff --git a/source/_integrations/shelly.markdown b/source/_integrations/shelly.markdown
index d67830f9890..89f2a158c31 100644
--- a/source/_integrations/shelly.markdown
+++ b/source/_integrations/shelly.markdown
@@ -310,8 +310,15 @@ Please check from the device Web UI that the configured server is reachable.
 
 ## Known issues and limitations
 
-- Only supports firmware 1.11 and later for generation 1 devices
+- Only supports firmware 1.9 and later for generation 1 devices
 - Only supports firmware 1.0 and later for generation 2 devices
+- The following generation 1 devices only support firmware 1.11 and later (due to incompatible API):
+  - Shelly DUO
+  - Shelly Bulb RGBW
+  - Shelly Dimmer
+  - Shelly Dimmer 2
+  - Shelly RGBW2
+  - Shelly Vintage
 - Generation 1 "Shelly 4Pro" and "Shelly Sense" are not supported (devices based on old CoAP v1 protocol)
 - Before set up, battery-powered devices must be woken up by pressing the button on the device.
 - For battery-powered devices, the `update` platform entities only inform about the availability of firmware updates but are not able to trigger the update process.