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Q: Please explain internet speeds. I use Wi-Fi and I can plug in an Ethernet cable. The speeds are all over the place; sometimes it’s high sometimes it’s low. Why the difference? My upload speeds are from the lowest of .15 mb/sec to as high as 30 mb/sec on Ethernet. On Wi-Fi it’s from .5 mb/sec to 17 mb/sec. Don’t get me wrong, I am not complaining just interested in what makes the speeds change so much. I think it’s the traffic on the net at the time. The app that I use is Speed Test. It shows a circle and arches around a circle to show speeds.

– Charles M.
Shalimar, Florida

A: Sure, Charles, I can tell you a few things about Internet speeds. However, I must tell you that some of what you’re asking is going to call for a good deal of speculation and conjecture, because every ISP is different, every connection is different, and each communication technology (DSL, cable, etc.) is also different.

Let’s start with some terminology. The term bandwidth is often used to describe the available information capacity of a network connection. Home connections usually express the value as the number of bits that can be transmitted or received each second, and typical rates are in megabits per second, usually abbreviated as mb/sec.

It is very common for the outgoing data rate (going to your ISP) to be only a small fraction of the incoming data rate. That’s because home connections are not intended to transmit large amounts of data like a website does. When you contract with an ISP, you are usually given a tiered suite of options to choose from. Faster connection rates are more expensive. These speeds are never absolutely guaranteed. In fact, if you look, you’ll see they usually describe the speeds as “up to” a given rate. That means to me that it can be any speed slower than that number, and will never be faster.

You also need to remember that the data speed that you purchase is only the speed between you and your ISP. When you are measuring your connection’s speed, you are measuring the speed of every segment between the local machine and whatever is at the distant end, which is almost surely many segments past your ISP’s server. You never see all the many hops your data packets take to get to their destination, but it can be dozens. A slow-down on any one of these segments will affect your speed rating, and it is totally outside of either your control or the control of your ISP.

You are correct in saying that other network traffic is probably affecting you. This is especially true if you have a cable modem as opposed to a DSL connection. With cable, the bandwidth is split and shared repeatedly the farther the distance away from the ISP. With DSL you generally have a dedicated line back to a switch. The speed ratings on DSL may be a bit slower than cable, but they are more consistent. Finally, you should generally expect faster speeds from a hard-wired Ethernet connection than from Wi-Fi, particularly when doing things inside your own firewall, such as printing or transmitting file. To see why, you need look no further than the speed ratings on your router. Most hard-wired connections are 1 gb/sec (1000 mb/sec) where the fastest Wi-Fi speed, which would be 802.11n is rated at 300 mb/sec-450 mb/sec. That speed is still far faster than your connection to your ISP, however. Again, remember that all these numbers are theoretical maximums, and your results will vary.

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Well, that brings me to the end of It’s Geek to Me for 2015. There’s more to come in 2016! My year starts off with a personal appearance at the annual “Computer Tech Expo” on January 31^st at Northwest Florida State College. You can check out the entire schedule of events at www.nwfacug.org. There are plans in the works to expand my website to offer new features and services. There’s also a newsletter in the works. The column’s Facebook page and Twitter feed will continue to put out up-to-the-minute information, such as breaking tech news and Geek Alerts. If you haven’t connected, go to ItsGeekToMe.co and click on one of the links, and I’ll be seeing you in 2016!