You're going to do a demo of a network connected device in a new place? Bring your own network. If you can bring all the parts with you, that's even better -- a self-contained system that has no external dependencies is best.

If you absolutely need network connectivity, bring a cellular-wifi hotspot that you've already tested. Talk to the site organizer to find out what cell networks work there, and if you need to, buy a SIM in advance.

If you don't have an IT organization, you are the IT organization, so be a good one.