Use of VPN in public setting

I often take my laptop to a public wi-fi for use, and I connect through my VPN. However, I often get kicked off or disconnected, making it difficult to accomplish any real work. I do not have this issue when I connect with my home wi-fi. Is there a different standard of connection with public wi-fi versus the wi-fi I use at home? Do I need to utilize another system to connect? Thank you.
