Been helping a lot of customers and I hear it all. They almost always say its their ISP. They refuse its is their computers or router. Agressively refuse to try a direct connection into their modem. Not even knowing the speed they are paying for exactly.

So at what point after you have tried everything to figure out what is causing speed/wireless issues do you assume it must be the ISP?

Then how do you convince the customer as well?

After I have usually tried all of this:
Running netstat -b 5>activity.log to get a list of connected programs.
Running sfc /scannow
Checking the signal strength
Broadcasting the SSID
Disabling the firewall
Clearing the browsers
Checking for virsuses and spyware
Attempting a direct connection to the modem
Checking physical connections
Error Check under my computer
Defrag
a few registry fixes...


Then my way of showing proof are with several speed test like on speakeasy.com and testmy.net.

How about you?

Well wireless is a major issue. With me anyway. After a few years of using wireless,
and having half or more on my 6Mb speed disappearing, I finally went back to
the traditional ethernet cable and now back on my 6Mb. I tried all the channels from
1 to 11 and never got full speed. I'll never have my desktop back to wireless unless it
improves drastically. Even uploading files/photo's on email, it would drop.

Another factor is capping due to extreme downloading. The customer'll not tell you this
(if it's illegal). If the customer explains there Broadband package - here in UK with
BT for example, there's 3 packages:

Option 1:Basic 10Gb DL limit
Option 2: Heavy Usage 50Gb DL Limit
Option 3: Premium 100GB DL limit.

Asking the customer what package they have. Most of the users might have basic
package and going over their DL limit without knowing it, and being capped constantly
to 1Mb restricted speed.

There's so much stuff to narrow down when it comes to broadband speed issues.
I been there myself.

Well you could demonstrate the speed to them by going to a speed test site
eg http://www.speedtest.net/ (You may have other sites you can access - google 'speedtest' in your area).
The speed will differ depending upon the time of day, and how much traffic the ISP is experiencing. I explain it to low end people like this.
Think of mother pig with her babies.
If all pigglets are latched on then there is less flow of milk for all. If only one or two are latched on there is heaps of milk. (Usually slow first thing in the morning when 'businesses' connect, and at the end of a school day when the kids all log on at home.)
And yes, the person's plan. Lots of ISP's will 'cap' the allowed data download. And then slow them down to dial up when they go over.(Well they do here anyway).
And also it depends upon what sort of plan they are on. Here you can pay more money and subscribe to a faster download/upload plan. Investigate the person's plan.
And also, it may depend upon which 'server' the ISP has you on. Some ISP's have 'legacy' systems, and they havn't migrated all their customers to the newest system yet. One can usually fix this problem by upgrading/swapping to one of the ISP's latest/current plans.

And - all those tests that you have done - good, but really only a malware infection that will use up the bandwidth you are provided with and slow the speed down for other programs connecting.

You can also look for cable-modem (and other network-related) firmware updates (including motherboard).....if firmware is update-able. If firmware can't be updated, your client may be the one using "legacy" hardware when the ISP has upgraded.

One example; docsis1.0 compliant modems are still around and do cause perceived varying "bandwidth" issues if the ISP has upgraded their service. Some ISPs upgrade at faster rates than others and of course varies by country. And btw, the ISP customer help processes seem to be NOT equipped to debug at this level. Even the techs miss it.

Well I always come to the conclusion that it is the ISP's fault. But things here are different I assume. Speeds are nowhere near what Tam described and the supposed 3MB Download Speed that Choice Cable is offering never comes! Maybe twice a month I get near those seeds but it never stays like that, then again I'm using the modem through wi-fi... I'll have to connect it through ethernet and see if there's any difference, which I fairly doubt.

Cable bandwidth is shared with anyone on your "pipe".

If you have a lot of other people in your area using the same Cable internet service, there will be peak & high usage times resulting in lower speeds for everyone, unless the cable co has made its best effort to ensure everyone will see their "subscription" fees.

That is why I prefer DSL to Cable. Dedicated connection to the home.

Er. This is over two months old.

I used cable for years, and never had slowdowns, even during "peak" hours. I'd take cable over DSL any day.