Fixes to GetMTUWindows and GetMTUWindowsIpv6 (thanks mlt).

util.cpp

@@ -562,7 +562,7 @@ namespace net {
         return fallback;
     }
 
-    int GetMTUWindowsIpv6(sockaddr_in inputAddress, int fallback)
+    int GetMTUWindowsIpv6(sockaddr_in6 inputAddress, int fallback)
     {
         ULONG outBufLen = 0;
         PIP_ADAPTER_ADDRESSES pAddresses = nullptr;
@@ -645,7 +645,7 @@ namespace net {
             return GetMTUWindowsIpv6(inputAddress, fallback);
         } else {
             LogPrint(eLogError, "GetMTU() has failed: address family is not supported");
-            return result;
+            return fallback;
         }
 
     }