بیشترین مواجهه با این خطا رو بنده زمانی داشتم که یکی از Gateway های مابین ما تا مقصد مشکل داشتن ؛ (برای مثال یکی از روتر ها یا لینک های رادیویی سمت مخابرات ) در نتیحه آخرین Gateway نمیدونست باید پاکت ها رو به کجا ارسال کنه . در واقع نقطه ی بعدی ای وجود نداشت که بخواد به اون چیزی ارسال بشه .
جستجوی گوگل هم این نتیجه رو داد :
Case Study - Destination not unreachable
Situation: the client just installed a new router connecting to the Internet, but he could not access the Internet from any computers in the LAN.
Troubleshooting: When tried to ping the default gateway, it got reply. However, ping a public IP got "Destination not unreachable", for example,
ping 4.2.2.1
Pinging 4.2.2.1 with 32 bytes of data:
Reply from 192.168.1.1: Destination not unreachable.
Reply from 192.168.1.1: Destination not unreachable.
Reply from 192.168.1.1: Destination not unreachable.
Reply from 192.168.1.1: Destination not unreachable.
Analysis: when you ping a outside IP, you receive reply form the default gateway with “Destination not unreachable” message. That means the gateway doesn’t know where to send the packets. In other words, the router doesn’t have correct WAN IP or doesn’t setup a WAN IP. In our case, the router didn’t receive an IP from ISP and it listed 0.0.0.0. After renewed the DHCP and received an IP, all computers can access the internet.