Extensive listing of places to find key information such as your User UUID/GUID, Ethernet MAC, model identifier, and much more.
networking
Using Lookup, Ping, and Traceroute to work out why you can’t connect to a website. Is your ISP blocking it, perhaps?
Radio-frequency interference from USB 3 peripherals can cause problems with Bluetooth and 2.4 GHz Wi-Fi.
How can you tell whether your Mac supports Continuity, whether you bought an app from the App Store, and diagnose extension problems?
Further suggestions for setting your router up, to keep your local network safe, secure, and free from trouble.
Apple announced in June 2015 that OS X 10.11 and iOS 9 would support extensions to better deal with network congestion. What happened?
Half the time I start my iMac up, it reports that something else is using the same IP address. How can I fix that?
Does it help to unplug your network connection when checking suspicious email?
How does creating a new location in the Network pane solve network lockout problems?
Periodically, my MiFi dumps my Macs off the Internet connection. Why?
The Eclectic Light Company 