lower default MTU to 1392 to avoid stressing certain VPNs

include/enet/enet.h

@@ -213,7 +213,7 @@ enum
    ENET_HOST_RECEIVE_BUFFER_SIZE          = 256 * 1024,
    ENET_HOST_SEND_BUFFER_SIZE             = 256 * 1024,
    ENET_HOST_BANDWIDTH_THROTTLE_INTERVAL  = 1000,
-   ENET_HOST_DEFAULT_MTU                  = 1400,
+   ENET_HOST_DEFAULT_MTU                  = 1392,
    ENET_HOST_DEFAULT_MAXIMUM_PACKET_SIZE  = 32 * 1024 * 1024,
    ENET_HOST_DEFAULT_MAXIMUM_WAITING_DATA = 32 * 1024 * 1024,