For about two weeks my AT&T DSL download speed was a lowly 0.2 megs, down from roughly 1.5 to 2+ megs normally. The AT&T phone tech suggested the splitter/filter could be the cause. I connected the DSL cable directly to the phone jack and, voila, I got good speed. So I replaced the splitter/filter with the Radio Shack GigaWare Single-Line Duplex DSL Filter, with success. Three days later, though, the download speed is back down to 0.2 megs. I connected the DSL cable directly to the phone jack again, bypassing the new splitter/filter, and again I get normal (for my house) download speed of 1.5 to 2+ megs.
Is this the fault of a bum splitter/filter? Is something on the outside interfering with the splitter/filter? The old one worked for several years. I really have no idea what the problem is. (An easy solution, of course, is just to get Comcast as my ISP, but that doesn't really tell me what is causing the problem, and for a heavy video downloader, a tattletale like Comcast really isn't a good choice of ISP.)
The fact that every time you connect directly to the jack things improve suggests that the issue is not on AT&T's end. Are you absolutely certain you are using the right jack on the filter? One is for the phone, one is for the DSL modem.
For now the problem has been fixed: I talked by chat with AT&T after my posting. The tech determined there was indeed a problem on the line on the AT&T side. This morning download speed was back up to normal (for my neighborhood's modest DSL speed, roughly 2 megs) and I got a call from the AT&T field tech confirming that the line problem had been fixed. Unfortunately he did not explain to me what, exactly, the line problem had been. I'm keeping my fingers crossed.
I had connected the DSL and phone cables to their respective jacks on the old filter (which I had been using without any problem for several years) and then on the new filter. The telling thing was that initially there was no speed problem when I swapped out the old filter; it was only three days later that download speed crashed again. In all fairness, I am perfectly capable of connecting things bass-ackwards, although my idiocy turned out not to be a factor in this situation.