Please forgive my blatant lack of computer knowledge. My home wi-fi seems slow, always has, and I don’t know the cause. Certain webpages are very fast but others are slow, and videos frequently stop in the middle of play before re-starting. I have cable internet from Comcast. I don’t know the brand of modem or wireless router - are certain types faster? My laptop is one of the lower-end Dell Inspiron models. Could this be the problem? Thanks for any advice.
Just yesterday I got a letter from Comcast (I live in Chicagoland) telling me that they were doubling the speed of everyone’s Internet access. They instructed us to turn off the power to the modem for a minute and then reset any router which we were using. I did that last night and the Internet speed seemed a tad speedier. You might as well give this a shot.
They also informed us in the letter that we are all entitled to free McAfee anti-virus protection.
I would start by finding out where the slowdown begins.
Plug your laptop directly into the modem, not router. The go to the site http://www.speedtest.net/ to get a benchmark. Then plug your PC into the router (wired) and run the test. Repeat for wireless. Typical cable speeds should be 3000+ kbps download and 300+ kbps upload.
If slow through the router then you could need a new one. If slow via wireless could be weak signal.
If slow for all 3 tests then try to take your laptop to another location (wired or wireless hot spot, friend’s house) and see what the test yields. This will let you know if it is the laptop or your cable. A hot spot may use a different service so the speeds may be different. But, if you get a fast speed you know you have a problem at home.
Some variability in web access is to be expected, and is not by itself an indication of a problem with your system or your ISP service; an individual website can be fast or slow at the time of your access for any number of reasons.
I’d run a few connection speed tests over the course of a few days and at different times of day and then look at your average and any variations to see what your connection speed actually is before deciding what to do next. One source of these connection speed tests is at http://www.speedtest.net/
I’ve got comcast at home as well, and I’ll run this test tonight and post the results for you to look at when you run the test yourself. I don’t expect them to be the same, but if one result is several times faster than the other then that’s maybe worth calling Comcast about.
Chris
Also, see this just-posted Computerworld article: http://www.computerworld.com/action/article.do?command=viewArticleBasic&taxonomyName=Internet+Business&articleId=9126997&taxonomyId=71&pageNumber=1
Thanks, everyone, those kinds of suggestions were exactly what I was looking for.
Do you have security enabled on your router? If not, your neighbors may be hogging your bandwidth downloading porn. 
Yes, I do have the security enabled. No porn for the neighbors!
i actually worked on the technical side for a cable internet provider. There are a few other things you can check to make sure you are getting 100%.
I guess the first metric is to run a speed test when it’s acting up to see if you are capable of getting the bandwidth you are allocated. If you are, then chances are it’s just the site you are trying to access or a bottleneck in between. IE: if you live in Chicago and connect to a server in San Diego, it takes longer for the packets to travel across the country then if you connected to a server on the east coast (called latency). Streaming video is pretty sensitive to latency, and you can have latency issues even with a a ton of free bandwidth.
One thing to keep in mind as well, is that many large providors make use of accelerators and traffic shapers. These sit back and watch the traffic flowing across, making copies of common stuff (so you can download it from a machine close to you instead requesting the same thing across the country over and over) and reallocating bandwidth based on it’s type (ftp, http, ect.) So a speed test could show you drastic differences in speed then what you observer quering google.
If you have persistant problems with slow speed, there may be a signal quality issue involved. With a cable modem network, digital ethernet packets are converted to a digitaly encoded RF (radio frequency) signal and transmitted over coax back to a central head end that demodulates it back into digital ethernet packets. Basically, your data is being transmitted like DTV. Wifi esentially works the same way, except it broadcasts it through the air, instead of coax. Anyway, the point of all of this, is that if you have interference in that signal, data gets lost. The result is that packets get lost and need to be retransmitted. Obviously, if you have to transmit the same piece of data 5 times to get it through, you wind up taking 5x the bandwidth for that packet. It’s easy for packet loss to start choking down a connection.
What to look for and how to fix it:
Sources of signal loss at the modem can be as simple as bad fittings or loose connections. So make sure that the coax cable connecting the modem to the wall is secured strong finger tight. Also check to make sure that the barrel isn’t corroded or gummed up and that the stinger (the conductor inside the barrel) is about extends flush with the edge of the barrel. Idealy, you want a cable that is under 6’, as signal strength drops with longer runs of cable. Also make sure there are no places in the cable that are or have been kinked. Tight turns (tighter then 1" radius) can cause a signal trap and cause all sorts of issues, as can damaged insulation from previous kinks, which is mostly invisible to the eye. If in doubt, just replace the cable with a fresh piece of RG6. RG6 is a thicker cable that suffers less loss. Try to avoid RG59 if you can, as it is designed for analog signals and not for modern digital transmissions. A good way to diagnose the cable and your overall connection is to hook an analog TV up to the wall where your modem is plugged in and turn it to a low channel. If you get poor video or audio, you have a lot of noise in the line and either need a new patch of coax, or need the cable company out to test and repair. Remember though, that digital data is much more sensitive then analog video, so there still could be a problem even if the TV works fine. You can actually check the signal levels on most modems by plugging a computer directly into the modem and navigating to the debug page. Once you connect the modem and let your computer get an IP, just look in the network status page and find the gateway address. Put this ip address in your browser and it should (if your ISP didn’t disable it) pull up a page showing you your modem’s signal levels. You want an rx power around 0 +/- 5, and a tx power somewhere in the high 30’s or 40’s (above 50 and under 30 point to signal issues).
If you ever experience an issue where the lights on your modem start to flash then come back solid, check your cable first, then call the cable company to come fix their signal issue.
If your modem’s connection is good, then the next possible cause is loss in the wireless signal. Now I am neglecting malfunctioning equipment, but I have seen routers crap out and do this sort of thing. The first thing to check with wireless is to make sure that your laptop is close enough that you have strong signal. Weak signal drops your signal to noise ratio, meaning that it’s harder for the laptop and router to distinguish data from noise. The only way around this is to relocate the router or laptop, or build a can-tennat to focus the signal in a particular direction. Interference from other soruces can also reak havoc on wireless signals. Virtually anyhing that transmits RF can interfere. i’ve seen a modem placed in close proximity (sitting on top of) to the router cause interference. I’ve seen a router sitting on top of a PC by the power supply cause interferience. A good rule is if you are having issues, move the rotuer away from other electronics and see if it helps. Of course, also remember (as previously mentioned) that if you run an unsecured network, that your neighbor may be online using up your bandwidth. In which case I suggest you learn linux and do this: http://www.ex-parrot.com/~pete/upside-down-ternet.html
That’s a fairly basic run through. If you have any specific questions, feel free to PM me.