Why is my high speed internet suddenly back to a dial up mode?

What ? ? ? ~ ~ ~ JK

Who do have as an internet provider? Some will throttle back if you use too much bandwidth total for the month. Sounds like you answered yourself.

OK, will it rejuvanate itself at the first of the month? And how can I tell if I’m useing to much for the allotted time?
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Check with your ISP and the contract you have with them. I repeat, who do you have for internet? ?
If you think it might be a technical issue contact the technical services group for the ISP.

While most ISPs will limit your bandwidth after a certain amount of data transfer, most have a generous enough cap that a couple of hours a day of HD video won’t bring you over that limit, even if you throw a few DVD-ISO images and major game installs in there at 4–9 GB a pop. (I did ~44GB last month and my ISP didn’t care.) Generally, the only way to break most of those limits is if you are torrenting constantly. In fact, high data usage (like >100GB/month) is how they usually catch illegal file-sharing; torrenting/P2P eats a lot of bandwidth.

Of course, your ISP may be different and have a lower limit than mine, so the first thing I would do is check my terms of service.

Also, my router has a built-in function to track data usage over the last day, week, and month, as well as the ability to cap data usage itself without the ISP doing it for me (which would be important if I had a lower data limit than I do.). Your router may also have those functions. If not (or if you can’t get to it), you could run something like NetSpeedMonitor to track your usage.

Of course, a quick call to tech support may be in order anyways. Worst case scenario, they will tell you that you have been throttled for exceeding your limit, and what that limit is.

It appears that you are in the United States. I can’t really think of any ISP’s that throttle for using so little download with maybe the exception of Clearwire. If you were in Australia I could understand since their caps for the month are what I use in a day.

Do you happen to share the connection with roommates? A improperly configured Bittorrent client can absolutely destroy the connection for everyone else on the network.

jery has most accurately indicated how this stuff works.

I will point out however that with some ISPs, even using a torrent just ONE time is enough to throw up a flag on your account and the download (along with possibly your regular usage) will be instantly throttled. A lot of ISPs detect high data transfers or unusual usage patterns and smack you down.

Now then, you must be encountering some other problem because if you have DSL or Cable internet on a flat monthly plan, your usage isn’t very crazy. If you have satellite internet or some other type of cell phone based (tethering / mobile hotspot) internet, then yeah that’s your problem.

I don’t think you’re running a risk of ‘running out of bandwidth’ with a regular ISP. Call and ask what’s up with your low speeds and go from there.