And here's the output from dumping the certificates used by that site:
Code:
openssl s_client -showcerts -connect aeon.co:443 < /dev/null **1*
CONNECTED(00000005)
depth=4 C = US, O = "Starfield Technologies, Inc.", OU = Starfield Class 2 Certification Authority
verify return:1
depth=3 C = US, ST = Arizona, L = Scottsdale, O = "Starfield Technologies, Inc.", CN = Starfield Services Root Certificate Authority - G2
verify return:1
depth=2 C = US, O = Amazon, CN = Amazon Root CA 1
verify return:1
depth=1 C = US, O = Amazon, OU = Server CA 1B, CN = Amazon
verify return:1
depth=0 CN = aeon.co
verify return:1
---
Certificate chain
0 s:/CN=aeon.co
i:/C=US/O=Amazon/OU=Server CA 1B/CN=Amazon
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
1 s:/C=US/O=Amazon/OU=Server CA 1B/CN=Amazon
i:/C=US/O=Amazon/CN=Amazon Root CA 1
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
2 s:/C=US/O=Amazon/CN=Amazon Root CA 1
i:/C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./CN=Starfield Services Root Certificate Authority - G2
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
3 s:/C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./CN=Starfield Services Root Certificate Authority - G2
i:/C=US/O=Starfield Technologies, Inc./OU=Starfield Class 2 Certification Authority
-----BEGIN CERTIFICATE-----
MIIEdTCCA12gAwIBAgIJAKcOSkw0grd/MA0GCSqGSIb3DQEBCwUAMGgxCzAJBgNV
BAYTAlVTMSUwIwYDVQQKExxTdGFyZmllbGQgVGVjaG5vbG9naWVzLCBJbmMuMTIw
MAYDVQQLEylTdGFyZmllbGQgQ2xhc3MgMiBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0
eTAeFw0wOTA5MDIwMDAwMDBaFw0zNDA2MjgxNzM5MTZaMIGYMQswCQYDVQQGEwJV
UzEQMA4GA1UECBMHQXJpem9uYTETMBEGA1UEBxMKU2NvdHRzZGFsZTElMCMGA1UE
ChMcU3RhcmZpZWxkIFRlY2hub2xvZ2llcywgSW5jLjE7MDkGA1UEAxMyU3RhcmZp
ZWxkIFNlcnZpY2VzIFJvb3QgQ2VydGlmaWNhdGUgQXV0aG9yaXR5IC0gRzIwggEi
MA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDVDDrEKvlO4vW+GZdfjohTsR8/
y8+fIBNtKTrID30892t2OGPZNmCom15cAICyL1l/9of5JUOG52kbUpqQ4XHj2C0N
Tm/2yEnZtvMaVq4rtnQU68/7JuMauh2WLmo7WJSJR1b/JaCTcFOD2oR0FMNnngRo
Ot+OQFodSk7PQ5E751bWAHDLUu57fa4657wx+UX2wmDPE1kCK4DMNEffud6QZW0C
zyyRpqbn3oUYSXxmTqM6bam17jQuug0DuDPfR+uxa40l2ZvOgdFFRjKWcIfeAg5J
Q4W2bHO7ZOphQazJ1FTfhy/HIrImzJ9ZVGif/L4qL8RVHHVAYBeFAlU5i38FAgMB
AAGjgfAwge0wDwYDVR0TAQH/BAUwAwEB/zAOBgNVHQ8BAf8EBAMCAYYwHQYDVR0O
BBYEFJxfAN+qAdcwKziIorhtSpzyEZGDMB8GA1UdIwQYMBaAFL9ft9HO3R+G9FtV
rNzXEMIOqYjnME8GCCsGAQUFBwEBBEMwQTAcBggrBgEFBQcwAYYQaHR0cDovL28u
c3MyLnVzLzAhBggrBgEFBQcwAoYVaHR0cDovL3guc3MyLnVzL3guY2VyMCYGA1Ud
HwQfMB0wG6AZoBeGFWh0dHA6Ly9zLnNzMi51cy9yLmNybDARBgNVHSAECjAIMAYG
BFUdIAAwDQYJKoZIhvcNAQELBQADggEBACMd44pXyn3pF3lM8R5V/cxTbj5HD9/G
VfKyBDbtgB9TxF00KGu+x1X8Z+rLP3+QsjPNG1gQggL4+C/1E2DUBc7xgQjB3ad1
l08YuW3e95ORCLp+QCztweq7dp4zBncdDQh/U90bZKuCJ/Fp1U1ervShw3WnWEQt
8jxwmKy6abaVd38PMV4s/KCHOkdp8Hlf9BRUpJVeEXgSYCfOn8J3/yNTd126/+pZ
59vPr5KW7ySaNRB6nJHGDn2Z9j8Z3/VyVOEVqQdZe4O/Ui5GjLIAZHYcSNPYeehu
VsyuLAOQ1xk4meTKCRlb/weWsKh/NEnfVqn3sF/tM+2MR7cwA130A4w=
-----END CERTIFICATE-----
---
Server certificate
subject=/CN=aeon.co
issuer=/C=US/O=Amazon/OU=Server CA 1B/CN=Amazon
---
No client certificate CA names sent
Peer signing digest: SHA512
Server Temp Key: ECDH, P-256, 256 bits
---
SSL handshake has read 5188 bytes and written 433 bytes
---
New, TLSv1/SSLv3, Cipher is ECDHE-RSA-AES128-GCM-SHA256
Server public key is 2048 bit
Secure Renegotiation IS supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : ECDHE-RSA-AES128-GCM-SHA256
Session-ID: E6E6AEEEC288A6367BE3492AE8D130E3BCA52EB8BB42C89AC1D1150F2536841C
Session-ID-ctx:
Master-Key: BB6E7D2C5BDA3A1FFCA6E0F4228D4930EDE7429ACB1A16FB65433D101B00BD8F5A8D699058D60CA7C71DF48E978F1D28
Key-Arg : None
PSK identity: None
PSK identity hint: None
SRP username: None
TLS session ticket lifetime hint: 300 (seconds)
TLS session ticket:
0000 - 7a 18 52 6a f2 7f 07 44-6d fb 16 47 ea e6 d8 2e z.Rj...Dm..G....
0010 - 90 5b 40 47 f7 be 3b 4c-22 ff 4f 29 3a f6 f4 63 .[@G..;L".O):..c
0020 - e1 73 9d bf 9a b8 57 23-8b 3f fb 5d d8 d6 b9 eb .s....W#.?.]....
0030 - 52 73 a7 59 09 2c d1 2b-88 f7 de 8f f5 80 dc 72 Rs.Y.,.+.......r
0040 - 6c 6f c3 76 df d4 d2 c7-89 0a 3d bc 6e 83 a7 11 lo.v......=.n...
0050 - 64 3d 0e a2 35 dd bd 13-b7 ee de 07 4f 9a 89 ad d=..5.......O...
0060 - 92 c2 62 fc 65 db 57 da-6d b8 8e 53 8a 02 12 1a ..b.e.W.m..S....
0070 - dc 6e 73 1e cd c5 04 cd-92 64 c4 eb b2 45 b4 d2 .ns......d...E..
0080 - f7 84 fa 5d 20 91 81 a3-e5 99 53 0c 8e d2 39 33 ...] .....S...93
0090 - ed 62 20 f7 9e 44 d1 92-f3 66 5f ea 16 bd 15 46 .b ..D...f_....F
Start Time: 1468593649
Timeout : 300 (sec)
Verify return code: 0 (ok)
---
DONE
You have to check that all the certificates listed in that chain (after the first one, which is the site certificate itself) are installed on your computer.