diff --git a/coapthon/layers/messagelayer.py b/coapthon/layers/messagelayer.py
index f4cba32..da455bf 100644
--- a/coapthon/layers/messagelayer.py
+++ b/coapthon/layers/messagelayer.py
@@ -1,6 +1,7 @@
 import logging
 import random
 import time
+import socket
 from coapthon.messages.message import Message
 from coapthon import defines
 from coapthon.messages.request import Request
@@ -105,10 +106,11 @@ class MessageLayer(object):
             host, port = response.source
         except AttributeError:
             return
+        all_coap_nodes = defines.ALL_COAP_NODES_IPV6 if socket.getaddrinfo(host, None)[0][0] == socket.AF_INET6 else defines.ALL_COAP_NODES
         key_mid = str_append_hash(host, port, response.mid)
-        key_mid_multicast = str_append_hash(defines.ALL_COAP_NODES, port, response.mid)
+        key_mid_multicast = str_append_hash(all_coap_nodes, port, response.mid)
         key_token = str_append_hash(host, port, response.token)
-        key_token_multicast = str_append_hash(defines.ALL_COAP_NODES, port, response.token)
+        key_token_multicast = str_append_hash(all_coap_nodes, port, response.token)
         if key_mid in list(self._transactions.keys()):
             transaction = self._transactions[key_mid]
             if response.token != transaction.request.token:
@@ -151,10 +153,11 @@ class MessageLayer(object):
             host, port = message.source
         except AttributeError:
             return
+        all_coap_nodes = defines.ALL_COAP_NODES_IPV6 if socket.getaddrinfo(host, None)[0][0] == socket.AF_INET6 else defines.ALL_COAP_NODES
         key_mid = str_append_hash(host, port, message.mid)
-        key_mid_multicast = str_append_hash(defines.ALL_COAP_NODES, port, message.mid)
+        key_mid_multicast = str_append_hash(all_coap_nodes, port, message.mid)
         key_token = str_append_hash(host, port, message.token)
-        key_token_multicast = str_append_hash(defines.ALL_COAP_NODES, port, message.token)
+        key_token_multicast = str_append_hash(all_coap_nodes, port, message.token)
         if key_mid in list(self._transactions.keys()):
             transaction = self._transactions[key_mid]
         elif key_token in self._transactions_token:
diff --git a/coapthon/server/coap.py b/coapthon/server/coap.py
index 99d2757..3b14f5b 100644
--- a/coapthon/server/coap.py
+++ b/coapthon/server/coap.py
@@ -88,20 +88,21 @@ class CoAP(object):
                 mreq = struct.pack("4sl", socket.inet_aton(defines.ALL_COAP_NODES), socket.INADDR_ANY)
                 self._socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
             else:
+                # Bugfix for Python 3.6 for Windows ... missing IPPROTO_IPV6 constant
+                if not hasattr(socket, 'IPPROTO_IPV6'):
+                    socket.IPPROTO_IPV6 = 41
+
                 self._socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
 
                 # Allow multiple copies of this program on one machine
                 # (not strictly needed)
                 self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-                self._socket.bind((defines.ALL_COAP_NODES_IPV6, self.server_address[1]))
+                self._socket.bind(('', self.server_address[1]))
 
                 addrinfo_multicast = socket.getaddrinfo(defines.ALL_COAP_NODES_IPV6, 5683)[0]
                 group_bin = socket.inet_pton(socket.AF_INET6, addrinfo_multicast[4][0])
                 mreq = group_bin + struct.pack('@I', 0)
                 self._socket.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)
-                self._unicast_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
-                self._unicast_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-                self._unicast_socket.bind(self.server_address)
         else:
             if addrinfo[0] == socket.AF_INET:  # IPv4
                 self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)