Re: "This will only take a second..."
I recently had a call from my father-in-law, wherein his girlfriend's wifi password had been changed. It seems that her "tech guy" (it might have been her son, I wasn't really paying attention) had set it up, including getting her phone on it, but some time later had been doing configuration, and now nothing could get on the wi-fi.
I told them to call her ISP for support, because I could guess at solutions, and have them poke at things until it either worked, or would never work again; but her ISP would (presumably) know the solution off-hand and if they needed a tech on-site, they would be a lot closer than 4 states away.
I actually got thanked for being helpful, because her tech guy would always tell "Don't call them, I'll fix it."