Troubleshooting Your Network Connection

NOTE: If you are magically connected to the net again after any of these steps, make a note of it for the next time things suddenly stop working.

NOTE: You may need access to the net in order to collect some of the information needed, which is sort of a Catch-22. It can be very useful to have a friend with working net access do some searching for you.

Many of the steps you will take are attempts to answer the basic questions for debugging almost anything involving computers.

1. Is it plugged in?
2. Is it turned on?
3. Is it configured correctly?
4. Has anything changed that you know of? New cables? New software or hardware installed on your computer? Added another computer or router to your house? Neighbors added a new wireless computer/router?
5. Have you ever seen this behavior before? If so, what fixed it last time?

"Handwave" is Just Two Four-Letter Words

At any time while asking these questions (of yourself or someone else), be alert for a handwave – real or implicit. When someone waves their hand it often means that they are assuming that something is true without actually having tested it. Assume is a dirty word when trying to troubleshoot a problem. In air traffic controller school we would chant every morning, "Assume makes an ASS out of U and ME." (Yes, we really did that for six months.)

If you do spot a handwave about something ("Oh sure, the cable is plugged in just fine. No worries, Mate."), that should be the very next thing you check. You may be shocked at how often the item being handwaved is the problem (along with the person doing the handwaving).

This came up just a few days ago when I was trying to help out a friend. I asked if he had checked all of the cables and the answer I got back was a handwave – Yeah, yeah, yeah. It turned out there was a cracked connector on the cable connecting their router to their cable modem. Because of that, it had literally fallen out and was lying on the ground. As Homer Simpson would say, "D'oh!"

Understanding What Type of Problem You Have

Networking problems fall into one (or more) of the following categories:

• Cabling
• Hardware (routers, switches, network cards, etc.)
• Operating system issues (which are different for PCs and Macs)
• ISP (Internet Service Provider)
• DNS (Domain Name Service, the 411 of the net)
• Web site problems (i.e., you can't get to amazon.com because it's down)
• Radio interference (wireless nets)

Isolating the cause of your problem(s) requires an obsessive attention to detail and a willingness to question everything.

First Things First

If you have more than one computer in your house/office, can any of them reach the net? If yes, then you know the problem is closer to your computer. If no, then you will want to look at your primary connection to the net, such as cable modems, routers, and did someone forget to pay the network bill? (Yes, I have run into this twice).

Much of the time, a sudden loss of net connectivity is either power-related or cable-related. Maybe the cat knocked something over which pulled a cable out, or maybe the router is plugged into a socket controlled by a light switch which just got turned off. So the first thing to do is a quick check of 'Is it plugged in?' and 'Is it turned on?'

Every network is a little different, but here is a list of the most common things to check.

1. Ethernet cables (they look like slightly over-sized telephone cables) connecting anything to anything. Check both ends, wiggle them. Possibly remove each one and reinsert it until it clicks. If you have more than one cable/jack setup between your computer and your cable/DSL modem, check each one. Do it one wire at a time, and always plug things back exactly where you unplugged them from.
2. Power cords. Are your modem/router/switch lights on? Why not?
3. Coaxial cable (coax) (from the cable company) or phone line (for DSL). Check each connection. Is it tight?

Once you have checked your physical connections, do a quick check to see if you can reach the net. I use Google because it's a fast-loading page, plus the fact that if Google isn't reachable, probably nothing else is, either. (They did go down for about 45 minutes once, but it doesn't happen very often.)

Power Cycle the World

Routers and cable modems are computers, and they can crash or get 'wedged' just like any other computer. The following is probably overkill, but it will eliminate any 'simple' crash from your list of possible problems.

1. Shut down your computer.
2. Disconnect the power connector (not the ethernet cables!) on your router and your DSL or cable modem. Do not get the power cords mixed up; they are not interchangeable.
3. If you have an older cable modem, wait for two minutes before preceding.
4. Plug in your DSL or cable modem. The lights will blink in various happy patterns for up to a minute. When they settle down into a "normal pattern," proceed.
5. Plug in your router. It will also do its Happy Lights routine. When it settles down, proceed.
6. Restart your computer.
7. Try connecting to google.com.

Narrowing the Problem

Oh well, you didn't luck out on one of the easy items. Now you have to start digging into just where things stop working.

The following steps will fairly quickly narrow the problem down to a few possibilities.

1. Launch your web browser: MS Internet Explorer, Mozilla Firefox, whatever. It probably won't be able to connect to your start-up page, so just click cancel.
2. Try to connect to Google. If this works, go to the section on Application Network Problems.
3. Try connecting to Google using one of their raw addresses (64.233.187.99). If this works, but the previous step did not, then go to the section on DNS problems.
4. Try connecting directly to your router/firewall. (You do have one, don't you?) To do this you will need to know the router's IP address.

   On a Windows machine, the easiest way of finding the router's address is to go to Start>Network Connections (or Start>Settings>Network Connections if you are using the Classic Start Menu). Right click on either Local Area Connection or your wireless device (which may show up under a number of different names) and select Status. Note: if Status is grayed out, then the device is either not working correctly, is unplugged, or is otherwise misconfigured.

5. A small window will come up with two tabs at the top; click on the Support tab. You will see something like the following, but the numbers will probably be different.

   

   Your machine's address is the number shown for IP Address (Internet Protocol Address, the Internet equivalent of a phone number). Your gateway's address is, surprisingly, shown as Default Gateway. Write down your gateway's IP address.

   NOTE! If either of these numbers is either 0.0.0.0 or starts with 169.?.?.?, then your computer is not in communication with your router and that is the first problem you have to address. This is getting into the deep end of the pool, because there are so many possible reasons why you can't talk to the router. The simplest thing to try is double-check all of the wire connections between you and the router (and also check that it is turned on), then restart your computer. If you still can't connect, then you need my not-as-yet-written paper on Router Kung Fu.

   Bring up your web browser and enter the gateway's IP address into the location/address bar and press Enter. If you succeed in connecting, you will be asked for a user name and password. In MS Internet Explorer it will look like this:

   

   I Don't Remember the Password!

   Mind you, I don't actually want you to login (at least not right now) to your router, just see if you can connect to it. If you can connect, then it means all of your networking cables, switches, wireless radios, etc., are working up to the router. It does not necessarily mean the router itself is working correctly, just that you can get to it.

   Still, it's good to know your router's password for future reference.

   1. If you did not change it from the default (bad, bad), then you might find it in the Friendly Manual that came with your router. If you threw that out, you might google for it, something like "Linksys WRT54G manual." Failing that, try going to PortFoward.com and scan the list for your router's make and model. Click on the link. Look for a link to the "Default Guide for this router." (It should be in the first four paragraphs or so.) Click on that link. Search (Control-F in Internet Explorer) for 'password.' Write down the default username and password.
   2. If you did change the password, but you can't remember it, then you will have to force the router to restore its settings to the factory defaults. Go find that Friendly Manual to see how to do this for your particular router (it will probably involve pressing a reset button somewhere on the back), then go back to item #1.

   DNS Problems

   DNS is the "White Pages" of the Internet. Your computer does not actually connect to google.com, instead it does a "DNS lookup" of google.com and discovers its IP address (Internet Protocol) is 64.233.187.99 (or any one of several other addresses that google uses around the world). The point is, if DNS lookup doesn't work, you're not going anywhere.

   Unfortunately, the major ISPs (specifically AT&T and Comcast) often have massively overloaded DNS servers. You may have a blazing 6Mb/s connection to the net, but the DNS server you are talking to thinks it's rush hour in San Jose. I wish I had a simple fix for this, but for many of you the only answer is to complain to your ISP. You will probably end up talking to 'Shawn' in Mumbai, India, who will tell you that there is no problem. Yeah, right.

   If you are feeling adventurous, you can try manually setting your DNS servers to 4.2.2.2 and 4.2.2.3. If you don't know how to do this, you can use the Help facility to search for DNS. That's all I'm going to tell you here because (a) slow DNS is better than no DNS, and (b) if you screw up your DNS settings, then you will have no DNS.

   Application Network Problems

   This is a highly variable area, depending on which application you are having trouble with and which protocol(s) it uses.

   (To be continued.)

   Firewalls Are Not Always Your Friend

   Firewalls are designed to allow some data packets through, while blocking others. If some applications are working (i.e., your web browser) and others aren't, one possibility many people forget to check (including me) is their firewall(s). There are hardware firewalls and software firewalls, and you may have more than one of each. The more firewalls that are involved, the more difficult it can be to figure out what the h*ll is going on.

   Hand-to-hand combat with firewalls (i.e., configuring and/or disabling them) is a deep subject and highly specific to the firewall(s) you have in your system. Give us a call and we will try to talk you through this. Often, firewalls make Peter climb into the BuddyMobile and make a site visit in full Ninja attire.