diff --git a/epan/dissectors/packet-stun.c b/epan/dissectors/packet-stun.c
index 05e5bc03cb..577b95c413 100644
--- a/epan/dissectors/packet-stun.c
+++ b/epan/dissectors/packet-stun.c
@@ -66,6 +66,7 @@ void proto_reg_handoff_stun(void);
  * ===============================================================================================
  *  Message  | 0b00+14-bit        | 16-bit             | 0b00+14-bit, type= |                    |
  *  Type     | No class or method | No class or method | class+method       |                    |
+ *           |                    |                    | Method: 0x000-0xFFF| Method: 0x000-0x0FF|
  * -----------------------------------------------------------------------------------------------
  *  Transac- | 128 bits, seen     | 128 bits           | 32 bit Magic +     |                    |
  *  tion ID  | with MAGIC as well |                    | 96 bit Trans ID    |                    |
@@ -291,6 +292,9 @@ typedef struct _stun_conv_info_t {
 #define GOOG_PING               0x0080 /* Google undocumented */
 
 /* 0x080-0x0FF Expert Review */
+/* 0x100-0xFFF Reserved (for DTLS-SRTP multiplexing collision avoidance,
+ * see RFC7983.  Cannot be made available for assignment without IETF Review.)
+ */
 
 /* Attribute Types */
 /* 0x0000-0x3FFF IETF Review comprehension-required range */
@@ -418,6 +422,8 @@ typedef struct _stun_conv_info_t {
 #define GOOG_LOGGING_ID         0xff05
 /* 0xff06-0xffff Unassigned */
 
+#define MS_MULTIPLEX_TURN 0xFF10
+
 /* Initialize the subtree pointers */
 static gint ett_stun = -1;
 static gint ett_stun_type = -1;
@@ -766,11 +772,11 @@ dissect_stun_message_channel_data(tvbuff_t *tvb, packet_info *pinfo, proto_tree
         proto_tree_add_item(stun_tree, hf_stun_channel, tvb, 0, 2, ENC_BIG_ENDIAN);
         proto_tree_add_item(stun_tree, hf_stun_length,  tvb, 2, 2, ENC_BIG_ENDIAN);
         /* MS-TURN Multiplexed TURN Channel */
-        if (msg_type == 0xFF10 && msg_length >= 8) {
+        if (msg_type == MS_MULTIPLEX_TURN && msg_length >= 8) {
             proto_tree_add_item(stun_tree, hf_stun_att_ms_turn_session_id, tvb, 4, 8, ENC_NA);
         }
     }
-    if (msg_type == 0xFF10 && msg_length >= 8) {
+    if (msg_type == MS_MULTIPLEX_TURN && msg_length >= 8) {
         msg_length -= 8;
         offset += 8;
     }
@@ -849,14 +855,25 @@ dissect_stun_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboole
     if (msg_type & 0xC000) {
         /* two first bits not NULL => should be a channel-data message */
 
-        /* XXX: As of RFC 8656, Channel numbers outside the range 0x4000-0x4FFF
-         * MUST be dropped, whereas in RFC 5766 implementations MUST NOT drop
-         * reserved channel numbers. Rejecting such channel numbers (in particular
-         * the range 0x8000-0xBFFF) allows multiplexing with DTLS-SRTP on the
-         * same 5-tuple by preventing collisions. That would also allow us to
-         * set the conversation for non-heuristic STUN dissection on UDP if we
-         * see any STUN message, not just a TURN message type.
+        /* RFC 5764 defined a demultiplexing scheme to allow STUN to co-exist
+         * on the same 5-tuple as DTLS-SRTP (and ZRTP) by rejecting previously
+         * reserved channel numbers and method types, implicitly restricting
+         * channel numbers to 0x4000-0x7FFF.  RFC 5766 did not incorporate this
+         * restriction, instead indicating that reserved numbers MUST NOT be
+         * dropped.
+         * RFCs 7983, 8489, and 8656 reconciled this and formally indicated
+         * that channel numbers in the reserved range MUST be dropped, while
+         * further restricting the channel numbers to 0x4000-0x4FFF.
+         * Reject the range 0x8000-0xFFFF, except for the special
+         * MS-TURN multiplex channel number, since no implementation has
+         * used any other value in that range.
+         * This allows us to set the conversation for non-heuristic STUN
+         * dissection on UDP if we see any STUN message, not just a TURN
+         * message type.
          */
+        if (msg_type & 0x8000 && msg_type != MS_MULTIPLEX_TURN) {
+            return 0;
+        }
 
         /*
          * If the packet is being dissected through heuristics, we never match
@@ -889,6 +906,18 @@ dissect_stun_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboole
     if (captured_length < STUN_HDR_LEN)
         return 0;
 
+    msg_type_class = ((msg_type & 0x0010) >> 4) | ((msg_type & 0x0100) >> 7) ;
+    msg_type_method = (msg_type & 0x000F) | ((msg_type & 0x00E0) >> 1) | ((msg_type & 0x3E00) >> 2);
+
+    if (msg_type_method > 0xFF) {
+        /* "Reserved for DTLS-SRTP multiplexing collision avoidance, see RFC
+         * 7983. Cannot be made available for assignment without IETF Review."
+         * Even though not reserved until RFC 7983, these have never been
+         * assigned or used, including by MS-TURN.
+         */
+        return 0;
+    }
+
     /* Check if it is really a STUN message - reject messages without the
      * RFC 5389 Magic and let the classicstun dissector handle those.
      */
@@ -914,9 +943,6 @@ dissect_stun_message(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboole
     transaction_id_key[1].length = 0;
     transaction_id_key[1].key = NULL;
 
-    msg_type_class = ((msg_type & 0x0010) >> 4) | ((msg_type & 0x0100) >> 7) ;
-    msg_type_method = (msg_type & 0x000F) | ((msg_type & 0x00E0) >> 1) | ((msg_type & 0x3E00) >> 2);
-
     switch (msg_type_method) {
         /* if it's a TURN method, remember that */
         case ALLOCATE: