AVR Freaks

I have the Zero Touch Secure Provisioning Kit for AWS IoT, which includes one SAMG55 Xplained Pro, one WINC1500 Xplained Pro, one CryptoAuth Xplained Pro and one OLED Xplained Pro. I follow this instruction:

https://microchipdeveloper.com/iot:ztpk

The SAMG55 debug console shows:

VERSION:  AWS IoT Zero Touch Demo v2.2.4

(APP)(INFO)Chip ID 1503a0
(APP)(INFO)DriverVerInfo: 0x13521352
(APP)(INFO)Firmware ver   : 19.5.4 Svnrev 15567
(APP)(INFO)Firmware Build Oct  4 2017 Time 14:59:09
(APP)(INFO)Firmware Min driver ver : 19.3.0
(APP)(INFO)Driver ver: 19.5.2
(APP)(INFO)Driver built at May 26 2019  07:29:01

WINC1500 Version Information:
  WINC1500: Chip ID: 0x001503A0
  WINC1500: Firmware Version: 19.5.4
  WINC1500: Firmware Min Driver Version: 19.3.0
  WINC1500: Driver Version: 19.5.2

WARNING:  The ATECCx08A device has not been provisioned. Waiting ...
SUCCESS:  The ATECCx08A device has been successfully provisioned.

Attempting to connect to AWS IoT ...
  SSID:     TP-Link_1176
  Password: ABCDEFGH
WINC1500 WIFI: Connected to the WIFI access point.
WINC1500 WIFI: Device IP Address: 192.168.100.192
WINC1500 WIFI: DNS lookup:
  Host:       awtxolrg1v35h.iot.us-east-1.amazonaws.com
  IP Address: 52.1.37.99
(APP)(INFO)Socket 0 session ID = 1
SUCCESS:  AWS Zero Touch Demo: Connected to AWS IoT.

ERROR:    The AWS IoT Demo failed to connect with the MQTT connect message.
WINC1500 WIFI: Device Time:       2019/05/27 00:22:57
(APP)(INFO)Sock to delete <0>
SUCCESS:  AWS Zero Touch Demo: Disconnected from WIFI access point.
WINC1500 WIFI: Disconnected from the WIFI access point.

Attached is the Wireshark capture showing the disconnect by the AWS (frame #17). 

I am using the main demo project from :  https://github.com/MicrochipTech/aws-iot-zero-touch-secure-provisioning-kit

The cryptoauthlib is from this build:  https://github.com/MicrochipTech/cryptoauthlib/tree/b31ed52daf2260329a131da19f8cc40a4d32d150

At this point, I suspect there must be something wrong with the setup on the AWS side, but I have no clue where to even start looking for the problem.  If some of you have gone through this demo project, I would like to hear your experience. Thanks.