Ping and traceroute are excellent first tests, but they rely on ICMP and, for traceroute, on routers replying with ICMP Time Exceeded messages. Firewalls, including host firewalls on computers and servers, often block some or all ICMP. When that happens, the diagnostic tool fails while the real service, such as a website on TCP 443, works perfectly. You need to recognize this so you do not chase a problem that does not exist.
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