agree I would plug all into the router that is much safer anyway since the router will or should have a firewall in it. If it were the ones hooked to the router that had the problem it could be a bad router but if the one you have issues with is not plugged into the router that is what I would try first. One of the first things an ISP tech will tell you is power down your modem and router, disconnect them from all power let set for several minutes then replug and try. Let us know if plugging that one into the router works. You always want to put the router between the pc and the modem to give you the added protection in the router.

I sometimes get that message when I have a loose connection, either with my cable modem or the Linksys router. It will clear after checking the connections and/or pushing the reset button. Just my 2 c's. Bejay

first thing to always try is to power down everything the pcs, the router the modem pull the power on all of them then start up in this specific order after about a 5 min rest, power to the modem let it get fully lit up, then power to the router let it get fully lit up then power to your various computers. See if that helps very often it does. You might try doing it with the laptop near the router then move it where you want it to see if it keeps the signal. Also you may have to re-enter your passcode to your wireless network again in that laptop it may not have kept it if it has been off a long time.

As Brickeye said it could RF induced. To check plug a resistive load, such as a lamp, into the receptacle to see if you still have the problem. If so, then it sounds like a different issue. I guess it is possible there may be a nail going through the say the neutral & one of the twisted wire pairs(keep in mind it might just slightly be nicked & when the treadmill runs the vibration makes the two make connections). Check the voltages on the phone wires while the treadmill is running. You may want to do another test as well. Plug a hair dryer into the receptacle & see if you have the same problem. This is an inductive load as well & will generate RF noise but without the vibration. This is a long shot but easy to check. Also, plug the treadmill into another receptacle on the same circuit to see if the problem continues. And then plug it into a receptacle on a different circuit. And to continue this debug process plug the DSL modem into a different phone line jack & test it, then a different receptacle but same phone line jack & test it, then a different phone line jack & receptacle & test it. This will help determine if the problem is "unclean" power going to the modem or if the phone line is having noise coupled onto it. Are you using the same duplex receptacle to power the treadmill & DSL modem? Are they on the same circuit even if not on the same duplex receptacle? How close is the receptacle to the phone jack?