What Milo said
I had that one time and thought it was just a wek signal and called in a tech. He saw the week signal and tried various antrenna movements etc. But the first thing he did was to password protect it. After about 5 mins he reognized the real problem was a dead router and that the signal was coming from my neighbors smilar named router, which he had now protected with my new password !!!
He evenually made it all right
I now name my routers
"server not found" which seems to be unique among my neighbors