Unable to traceroute 'smtp.gmail.com'

Question

I've been trying to configure my NAS to send SMTP messages, but the transmission always seems to fail. To diagnose this problem I tried traceroute'ing "smtp.gmail.com:587"...

It always fails on the second hop:

kylemart@nas:/$ sudo traceroute -n -T -p 587 smtp.gmail.com
[sudo] password for kylemart:
traceroute to smtp.gmail.com (74.125.141.109), 30 hops max, 60 byte packets
 1  192.168.143.1  0.337 ms  0.753 ms  0.771 ms
 2  66.158.XXX.XXX  1.752 ms  1.497 ms  1.758 ms
 3  * * *
 4  * * *
 5  * * *
 6  * * *
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29  * * *
30  * * * 

(Note: The X's were manually inserted to mask the IP address.)

Am I going about diagnosing my original problem the correct way? If so, is this an ISP-related issue? None of my devices seem to be able to traceroute "smtp.gmail.com:587" while connected to my home network, but while connected to a mobile hotspot things work fine.

Answer 1

This was the solution I needed: https://community.netgear.com/t5/Nighthawk-WiFi-Routers/Outbound-Mail-Blocked/m-p/1359873/highlight/true#M65452.

In short, my router was being assigned an IP address that was blacklisted from using SMTP. The ISP had apparently mapped my router's MAC address to this blacklisted IP address, so I configured my router to use a pseudo-random MAC address. This resulted in the ISP giving my router a fresh IP address, and consequently solved my problem.

EDIT: Although traceroute seems to indicate things aren't working as expected. Here's the new output:

kylemart@nas:/$ sudo traceroute -n -T -p 587 smtp.gmail.com
traceroute to smtp.gmail.com (74.125.141.108), 30 hops max, 60 byte packets
 1  192.168.143.1  0.448 ms  0.968 ms  0.999 ms
 2  66.158.177.124  2.114 ms  2.032 ms  2.072 ms
 3  208.111.0.123  2.090 ms  2.073 ms  2.057 ms
 4  208.111.12.214  5.149 ms  5.181 ms  5.119 ms
 5  65.158.121.12  13.068 ms  13.095 ms  13.077 ms
 6  * * *
 7  * * *
 8  * * *
 9  * * *
10  * * *
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *
20  * * *
21  * * *
22  * * *
23  * * *
24  * * *
25  * * *
26  * * *
27  * * *
28  * * *
29  * * *
30  * * * 

Note: The IP addresses were manually (slightly) obfuscated.