> A while ago I suddenly had trouble connecting with Safari, after getting > email with Eudora a few minutes earlier. > > Network Diagnostics reported OK status (green light) on Built-in > Ethernet, Network Settings, and ISP, but orange or red on Internet and > Server. > > Cured by rebooting my router. > > But I would still like to know the cause. My guess was a glitch in the > ISP's DNS server. I did find it a bit odd that I had an OK connection to > the ISP but not to the internet.
Network Diagnostics' definition of "ISP" is misleading. It means it can talk to your configured DNS server, and that is likely to be your own router. (I've confirmed this with some testing.)
I've never worked out what the "Internet" indicator actually means. The "Server" indicator means that it got a valid response from Apple's server.
On my working connection, Network Diagnostics did the following:
- Ping my router. - DNS lookup for www.apple.com. - Ping www.apple.com.
If everything is running normally, I get green on everything.
If I tell my router to disconnect from the Internet, I get green on everything up to and including ISP, but red for Internet and Server. My router is my DNS server. It is returning error results to DNS lookups while the Internet is disconnected.
This suggests that the failure in your case was that your router had no connection to your ISP.
