Slow Internet Sometimes? Here's Why...

Category: Networking

An AskBob reader says: 'My Internet connection is usually great, but it seems to slow to a crawl at certain times, for no apparent reason. Is it likely that I have a virus, or are there other possible explanations for the slowdowns?' Yes, several! Read on...

Diagnosing a Slow Internet Connection

Unfortunately, intermittent problems can be difficult to diagnose, because they are not easily reproducible. Many different things can cause your Internet connection to slow down. Some of them are within your control, but many are not. Here are some of the common causes for slow Internet connections.

Too many users sharing one Internet connection can slow everyone to a crawl. If you are sharing a "high speed" connection on your home network, you may experience slowdowns when others in the house are using Youtube, streaming a movie or TV show, or playing a graphics-intensive online game. If you have a cable modem, you are sharing a connection with other households in your neighborhood. If the slowdowns happen around the time that kids are getting home from school, or weekday evenings between 8pm and 10pm, it's likely that your cable TV company has oversubscribed the equipment that serves your area.

This type of slowdown is unique to cable internet, because the service provider may not have allocated enough bandwidth for a particular neighborhood. If the connection becomes saturated when many people are using the service, speeds will drop. A fiber-optic solution such as Verizon FIOS will not be susceptible to this type of problem, because each subscriber has an "end-to-end" connection to the central office.

Slow Internet Connection

An unknown program may be downloading or uploading data in the background without your knowledge. It might be something innocuous, like a backup operation, Windows Update, or it could be a virus, trojan, or other type of malware program. If your computer is ensnared in a botnet, it could be pumping out volumes of spam without your knowledge. See What Is a Botnet? for more on that. Scan your system with anti-malware software to uncover such problems.

Outdated software can result in a slow Internet connection. Make sure your operating system is up to date with the latest bug fixes and security patches. Visit the Windows Update website and see my related article Keep Your Software Updated (or else...) to make sure everything is up to date.

Another possible issue could be a data cap. Some service providers will "throttle" your connection speed if you exceed your monthly allotment of data. This happens more often on mobile phones and satellite internet connections, but can also happen on wired home internet service. Some service providers limit download speeds during peak usage times, or if a user has recently downloaded a large amount of data. This can happen even with "unlimited" data plans. Check with your service provider if you think your speed may have been slowed down due to a data cap issue.

Checking Under The Hood

You can check your Internet download and upload speeds with You may find out that your actual speed is much lower than what you service provider has promised!

A slow Internet connection may be part of an overall PC performance drop. Your computer may need some general maintenance. My tips on Seven Free PC Maintenance Tools will help you find software to use for those tasks.

A misconfigured router may slow down your connection. Reboot the router to see if that will clear up the problem. You can also try resetting the router to its factory defaults and configuring it all over again. Networking hardware is pretty durable but a router or network adapter can fail. Often hardware dies a slow death, with gradually slower connection speeds being one of the symptoms. Try a different router or network adapter to see if that helps. I had a cable modem that just seemed to get tired after running for a few days. Turning it off and then on again solved my sluggish Internet connection problem, and after I got a replacement from the cable company, the problem was gone for good.

There may be a problem in the wire connecting your home to your ISP, or in the configuration of your ISP's equipment. Ask your cable or telephone company to conduct a line test. This may require scheduling a visit from a technician. A few years back, my cable internet service was intermittent, and a technician discovered that the incoming cable was rubbing against a tree branch, causing it to fray. Squirrels also seem to enjoy nibbling on Internet infrastructure.

Sometimes there are traffic jams on the Internet; there's not much you can do about those. If some websites load speedily while others are slow, it could be there is a bottleneck between you and the slow-loading sites. Or the site you want to access could be bogged down with too many visitors. You just have to wait for the problem to be fixed, or try at some other time of day.

Slow Internet connections on mobile devices such as an iPad or smartphone are almost always caused by heavy network traffic or weak signal. There's nothing you can do about network traffic except wait for it to subside. Moving outdoors and away from tall buildings can help you get a stronger cellular signal. Wifi may be spotty in certain areas of your home. Satellite internet connections can be affected by heavy rains, thunderstorms, and solar activity.

Do you have other tips to help with slow internet connections? Post your comment or question below...

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Most recent comments on "Slow Internet Sometimes? Here's Why..."

Posted by:

10 Nov 2020

Because of all the people working from home, schooling from home, etc., a lot of ISPs are overloaded during certain times of the day. And the ISPs can't easily just upgrade their networks. In my area, several of the fiber nodes (the locations where there is a conversion from fiber optics to cable) are overloaded. So I am constantly hearing from people complaining about how slow their Internet has gotten. My particular segment is fast, but neighbors a few blocks away on a different segment see slowdowns all the time. Especially on upstream which affects your ability to have reliable Zoom and other video chats.

Of course as Bob said, it could be the usage inside your house, it could be your WI-FI or cable modem, it could be wiring, it could be you need your ISP to come and check things. I know it sounds stupid but try turning off and on your modem/router. That causes it to get the latest updates from the ISP.

Posted by:

10 Nov 2020

"If some websites load speedily while others are slow, it could be there is a bottleneck between you and the slow-loading sites."
I have recently found that hibernating my computer too many times causes problems with my browser, and particularly with one website with a database which I use often. The cure is to close down the computer and open 'clean'. I guess that will also clear the cache in the browser which can also cause slow surfing if your device is not shutdown often.

Posted by:

10 Nov 2020

hey Bob,
do you have a better internet speed test link? I for SURE don't want a freeking yahoo toolbar i have to add or allow it access to my computer just to perform a simple test.
thanks bro, keep the newsletters coming!

Posted by:

10 Nov 2020

try this one instead.... no need to add any extensions, or agree to anything intrusive like yahoo.

Posted by:

10 Nov 2020

Bob, there are a lot of causes that you omit to mention — it can be because there's an 'r' in the month, because there isn't an 'r' in the month, because the day of the week ends with a 'y', because ... well, you get the picture...
...Speeds promised, like disk sizes, are always exaggerated by choosing "kilo-" to mean either 1,000 or 1,024 (whichever serves them best in a particular context) ... and they probably only guarantee that you'll get "UP TO" 100% of that speed anyway.

Posted by:

Mark Neville
10 Nov 2020

I have a problem with one computer that speed test shows 500 Mbps download and 30 Mbps upload. I am using wired ethernet back to the Linksys mesh router. Other desktop computers on the same network measure 500 up and down. And the router itself also measures 500 up and down, which is the speed I am paying for. I can’t figure out how to find what is the weak link in the lan and fix it.

Posted by:

10 Nov 2020

I clear my brower cache frequently. Most websites seem to work better that way. If the internet is slow and I haven't restarted for awhile, I will do that. Sometimes I realize it is the internet traffic, and I just go on to something else.

There are only two of us here, so traffic in the house is not a problem, even if we are both on our computers. When we are streaming videos, we are watching the same TV. We both close our browsers when we are not using our computers, so we rarely have a speed problem.

Posted by:

10 Nov 2020

Before you use the link that @Pink sent out. Which was -
You might want to read the privacy page 1st. Then decide if you want to continue on.

Posted by:

Dennis Flinn
10 Nov 2020

I have noticed that a number of times people have concerns about the internet speed they neglect to factor in that they have a VPN running.

Posted by:

11 Nov 2020

Willy: That was a wise post of caution that you sent relating to the speed test recommendation by pink. I too read the "rules" and decided not to go there.

In reality it may be a safe site, but what you must accept to use it raises several concerns. I suggest that AskBob should check out directional links before allowing them to be included in posts, but since that would require more time than reasonable, it is simply User Beware and use some common sense.

Posted by:

d rbodz
12 Nov 2020

I use for speed test. You can choose different servers for results

Posted by:

Charless Hadden
18 Nov 2020

This junk is children's talk and has nothing to do with nothing. I have 300 Mbs dD/l speed and still can't watch a streaming video. Just sits there buffering. Now that is a problem and I have the same thing on my smart TV. It is the IPS throttling the feed. It is silencing free speech.

Posted by:

20 Nov 2020

Charless Hadden, who says you have 300 Mbps? Just because your ISP says so doesn't mean you actually have it. First reason is that the 300 is a best case theoretical number. You'll never come close to getting that (at least not in a typical home environment). Next, the slowest device on your network will drag down your effective speed. Most devices, especially older ones are capped at 100Mbps, such as a Roku box, or a router, or older computer, or a smart TV. WiFi will also slow down your speed, as opposed to a fully wired network. But, 100Mbps should be plenty to do streaming, so you have something else going on.

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