Network Troublehooting

If you are having network problems, take a "divide and conquer" troubleshooting approach. So, think of the links in the network chain, and start trying to narrow down where the problem is. For example, if you can't load a webpage, here's the links you are going through:

A. Browser
B. Operating System (Windows or Mac OS)
C. Wireless or wired adapter on computer
D1. Wireless signal to access point (if you are on wireless), or
D2. Wired ethernet cable to router (if you are wired)
E. Wireless access point's wired connection to main router (if you are going through a wireless access point)
F. Main router wired connection to Cable Modem (e.g. IP address 192.168.1.1)
G. Cable Modem connection to ISP
H. ISP connection to website's server
I. Website's server

Or, they may all be working, but just slow.

So, start eliminating or narrowing down links in the chain. Here's an example:

Can you connect but it is slow?

Go to http://speedtest.net
Connect to the Tucson server and run a test
Record the upload and download speed
These should match or exceed what you are paying for from the ISP.
If they are slow, then you can "divide and conquer" and determine whether it is in the home network or external internet/ISP. For example (see below for details):
- Plug a laptop directly into the main router, and run speedtest again. If you get faster speeds, the problem is a bad cable/wireless connection somewhere inside the main router.
- If it's still slow from the main router, plug the laptop directly into the cable modem. If you get faster speeds, the problem is the connection to the main router. If not, then the problem must be the ISP, and you should open a support ticket.

Can you see other websites?

Open google.com in browser.
If that works, H or I are the problem. A-G are working, and the websites server (or the internet close to it) must be having problems.
If it doesn't work, move down the chain and try to eliminate the browser (A) as a problem

Can you ping google?

open command prompt and ping google:
```
  ping google.com
```
If this works but the browser didn't load google.com, then the browser (A) is the problem. Use a different browser.
If this doesn't work, try pinging the router to eliminate A-E as a problem

Can you ping the main router?

open command prompt and ping google:
```
  ping 192.168.1.1
```
If this works, then the problem must be in the at the main router, ISP, or the internet/website (F-I). Skip down to "Can you connect when wired directly to the cable modem?" to eliminate F as a problem.
If this doesn't work, move down the chain and try to eliminate the local computer (A/B/C/D) as a problem

Can you connect from another computer?

Open google.com from a different computer.
If this works but didn't work on the original computer, then theres a problem with the OS network config or network connection (B/C/D) on the original computer. If the original computer is on wireless, try connecting via wired to eliminate C and D.
If you can't load google.com from another computer on the internal network, then problem must be in D-I.

Can you connect via a wired connection to the main router?

Try to eliminate the wireless signal and wireless access point (D1) as a problem (if you are going through one). Take a laptop, and plug directly into the main router via an ethernet cable, and try to ping google.com.
If this works, then somethings wrong with either the wireless access point, the access point's connection to the main router, or the wireless signal strength.
If this doesn't work, move down the chain and eliminate the main router and configuration (F) as a problem

Can you connect when wired directly to the cable modem?

Plug directly into the cable modem with an ethernet cable (you'll have to temporarily unplug the main router's cable).
You should automatically get an IP address from the ISPs servers (check with ipconfig /all)
Try to ping google.com (or do a speedtest.net test).
If this works, then there's a misconfiguration in the main router or its connection to the cable modem (F). Check/replace the cable, and power-cycle (unplug/replug/wait one minute) the router, and check the configuration.
If this doesn't work, try to power-cycle the modem (unplug/replug/wait one minute), and see if it works.
If this still doesn't work after power-cycling the modem, then the problem is in the ISP or internet itself (H or I). Call the ISP, open a ticket, and tell them you are having problems even when you have a wired connection directly to the modem (so they don't waste your time trying to prove it isn't your local network, which you've already done).

thewoolleyman/network_troubleshooting.markdown