network problems keep getting alert:no internet connection on different machines

help.

i have a home wifi network. the router has been replaced in the middle of these problems so its not that.

the main router runs a 100 meg connection which serves my iMac (wired) plus wifi connections for wife's macbook, 2 iPads, 2 iPhones.


i have a wifi extender Dlink, in the bedroom pushing the wifi to my mac mini in the bedroom which streams plex to the tv in there.

i keep getting, on different machines, a wifi logo which has an exclamation mark in it, and when i click on the wifi login i get "alert:no internet connection"


this can happen on any machine.