Help, my laptop won't stay connected to the wifi?

Okay I have a Lenovo, I think g580 i don't know. It connects to my wifi at home but at my friends house it won't stay connected for long. It only allows me on for 10 minutes to an hr then it disconnects. I can reconnect it but it does it over and over again. My cell phone works completely fine and so does all of theirs. I've checked everything i could but I don't know what is up.