A 6 month old D-Link modem router (2370U). What possible reasons could there be for this horrible, frustrating performance? Line stats don't seem bad to me, either.

Code:

    SNR Margin (0.1 dB):    343    292
    Attenuation (0.1 dB):    130    83
    Output Power (0.1 dBm):    167    124

 

Are you sure that it's not some program that's uploading something? If you're sure of that, either get another modem/router to test that it's not the router in itself, and/or call your ISP to make sure that it isn't a fault on their end. Also, this is a DSL/ADSL connection right? If so, do you have a splitter? Those things are the first suspect most of the time. Do you also have random losses of sync or is it just the high ping? Taking a look at the log is also a good idea, if you can acces that on your router.

Those values you posted seem fine from what I can see, although that also depends on the speed of your up- and downstream, since with higher speeds the SNR is typically lower than with lower speeds.

 

Yeah. No uploads, downloads and minimal network use at the time. (Or, at least, that's what the task manager showed me.)

Also, in general my network pings are exceedingly jumpy - I can get 50ms in the same ping as 400 ms. The ISP (it's a crappy ISP, but is cheap and doesn't throttle me) has extensively checked the backend, and they say it is all fine. It's not, but after pestering them for nearly two weeks, nothing more is happening.

So, essentially two problems: the router ping one which I feel is router related, but is hard to reproduce (it happens occasionally, and not everytime the router has been on for a long period), and exceedingly jumpy ping.

 

This is highly unlikely. Two months ago, I (auduously) got the ISP to fix the phone when one of their more technically-oriented people told me that my line was absolute shit. Reduced average ping from 600ms~ to around 200ms~.

I'm thinking this, too. It's a pretty cheap router and is really not positioned in the most well-ventilated of places.

Phone jack, with a nice little splitter. My pings jump around a lot and takes ages to reach just the first hop. (That is not my router). I'm pretty sure there's something funky going on, either with the router (which I'm going to test soon by getting a friend's), or the phone line itself, but my ancient government-owned ISP lack the interest and the technical support people who could diagnose this effectively. (The only reason to stick with these people is that there is no cap - other ISPs are gouging us with caps.)

Usually google.com. Live in India.

Do this pretty regularly.

Already using google DNS.

Thanks for the extremely comprehensive reply!

 

Are you on BSNL/VSNL by any chance?

If you are, then the problem is intentional on the ISP's part but most people who you'll talk to on the phone won't know about it.
The longer you're online, the lesser your priority is. I found this the hard way. Apart from the heavy jitter, inconsistent quality and generally bad speed, this is one of the regular problems I face. I have to restart the modem atleast once a day to maintain the speed.

The only saving grace is the speed is pretty much constant.