'To really figure out what's affecting your Wi-Fi network's speed, you need to buy expensive equipment.'
You can buy expensive networking hardware and software analytics tools like MetaGeek's Wi-Spy DBx Pro spectrum analyzer. But many inexpensive (or free) tools can also shine a light onto the status of your network.
Mac OS X users can simply hold down the Option key while clicking the Wi-Fi icon in the upper-right corner of the menu bar. When you do, you'll see many more details about your network: for example, the ethernet standard that your network is using (802.11 a/b/n/ac), the channel that your router is on, the type of security that's enabled, and the transmission rate and strength of your wireless signal via the RSSI (received signal strength indicator).
Another great tool for understanding your network is Objective Development's $35 Little Snitch (4.5 of 5 rating). This utility will alert you when any app or process tries to access the Internet. You might be surprised by how many applications try to connect to your network. Little Snitch's status screen also shows you connected apps as well as how much data they are sending and receiving. If your network seems sluggish, Little Snitch gives you an easy way to spot bandwidth hogs.
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