diff --git a/Docs/UDPStreamer.md b/Docs/UDPStreamer.md
index f809b3c..28eb48f 100644
--- a/Docs/UDPStreamer.md
+++ b/Docs/UDPStreamer.md
@@ -36,7 +36,8 @@ thread.
 
     // Multicast (optional — omit for unicast mode)
     MulticastGroup  = "239.0.0.1"  // IPv4 multicast address (224.0.0.0/4)
-    Interface       = "eth0"       // Multicast-bound interface (mandatory when MulticastGroup is set)
+    Interface       = "192.168.1.10" // Local IPv4 address of the outgoing interface
+                                   //   (mandatory when MulticastGroup is set)
     DataPort        = 44501        // UDP port for multicast DATA (default: Port+1)
 
     // Publishing mode (optional)
@@ -87,7 +88,7 @@ thread.
 | `Port`           | uint16 | 44500            | UDP server port (unicast) or TCP control port (multicast). Values ≤ 1024 produce a warning. |
 | `MaxPayloadSize` | uint32 | 1400             | Max payload bytes per UDP datagram (min 18)                                 |
 | `MulticastGroup` | string | *(absent)*       | IPv4 multicast address (e.g. `"239.0.0.1"`). Must be in 224.0.0.0/4. Absent or empty = unicast mode. |
-| `Interface`      | string | *(absent)*       | Network interface for multicast binding (e.g. `"eth0"`). **Mandatory** when `MulticastGroup` is set. |
+| `Interface`      | string | *(absent)*       | Local IPv4 address of the interface multicast DATA leaves from, in dotted-quad form (e.g. `"192.168.1.10"`, or `"127.0.0.1"` for loopback-only testing). **Not** an interface name — `"eth0"` is rejected. **Mandatory** when `MulticastGroup` is set. |
 | `DataPort`       | uint16 | Port+1           | UDP port for multicast DATA datagrams. Ignored in unicast mode.             |
 | `PublishingMode` | string | Strict           | `Strict`: send every RT cycle. `Accumulate`: batch until size/time limit. `Decimate`: send every Nth cycle. |
 | `MinRefreshRate` | float64| —                | Flush frequency in Hz. **Required** when `PublishingMode` = `Accumulate`.   |
@@ -147,7 +148,14 @@ CONNECT evicts the previous client.
 ### Multicast
 
 Enabled by setting `MulticastGroup` to a valid IPv4 multicast address (224.0.0.0/4).
-The `Interface` parameter is **mandatory** and specifies the network interface to bind.
+The `Interface` parameter is **mandatory**. It is the local IPv4 address of the
+interface DATA datagrams leave from, given in dotted-quad form — it sets
+`IP_MULTICAST_IF` on the data socket and is parsed with `inet_addr()`, so an
+interface *name* such as `"eth0"` is rejected and `Initialise` fails.
+
+Receivers must join the group on the matching interface. A receiver that joins
+with `INADDR_ANY` lets the kernel pick the default-route interface, and it will
+silently receive nothing if that is not the interface named by `Interface`.
 
 The server opens a TCP listener on `Port` for control traffic and a UDP socket aimed at
 `MulticastGroup:DataPort` for data traffic. The client:
@@ -253,7 +261,7 @@ PrepareNextState()          ← opens UDP server socket, starts background threa
     Class            = UDPStreamer
     Port             = 44500           // TCP control port
     MulticastGroup   = "239.0.0.1"     // Enables multicast mode
-    Interface        = "eth0"          // Mandatory for multicast
+    Interface        = "192.168.1.10"  // Local IP of the outgoing interface (mandatory)
     DataPort         = 44501           // UDP data port (default: Port+1)
     MaxPayloadSize   = 1400
     PublishingMode   = "Accumulate"