An ISP in Wales recently solved their town-wide DSL problem by locating and disconnecting a resident’s old TV. It’s an extreme example of a common problem with DSL service: DSL signal is very touchy and vulnerable to interference. And that interference can be caused by so many different things along your phonelines. If you have persistent DSL problems, here’s some troubleshooting info for you:

  • Connect your DSL modem’s phoneline directly to the wall jack. Only use the phone cable provided with the modem by your ISP. That phone cable from the dollar store or that line that came with your fax machine may not be an adequate replacement.
  • Do NOT route the modem’s phoneline through a surge protector. Avoid connecting the modem’s phoneline to duplexers or splitters or couplers, unless directed by your ISP. If possible, eliminate splitters and couplers elsewhere in the house.
  • Disconnect old fax machines, answering machines and rotary telephones elsewhere in your house. Really, anything attached to a phone jack in your home could be offending your DSL modem. If your DSL behaves better after detaching some of these devices, you can reconnect them one at a time to figure out which is to blame.
  • All other devices connected to your phonelines must run through DSL filters. These filters are typically supplied by your ISP — call them if you need some! An unfiltered device can upset your DSL modem, even from across the house. Your DSL modem should not be filtered, unless your ISP supplied you with a special duplexer for attaching both a modem and a phone to the same jack. That sort of dongle is actually filtered on one side (for a phone) and unfiltered on the other (for your modem).

Also, make sure not to stack your DSL modem on top of your router or any other electronics. Stacking can lead to overheating, which causes frequent outages until the modem is totally cooked!

Each time you make a change or improvement to your wiring, reboot your modem. But do NOT use any hard-to-reach Reset button, unless directed by your ISP. If you use the Reset button (usually by inserting a toothpick into a hole on the rear of the modem), you may erase important settings and make your situation worse.

If all else fails, it may be time get a new modem. Besides normal wear and tear, DSL modems degrade due to power surges that travel over the phone lines. I recommend you go to your ISP for your replacement modem, to ensure that they support you with any future issues.