Any gadgets that you suggested to your friends later found out was trash

I've recently suggested a wifi extended/repeater to a friend of mine as his wifi signals stuggles to reach his room. I've read about wifi repeaters and suggested one to my Friend. He bought one hearing my suggestion and fu*ked up.

The repeater caused huge jitter and latency and made the internet unusable. Luckily he doesn't remember who suggested it🤷‍♂️