[stoltzmann]

>connected to their wifi

Absolutely, it's their own network.

>being brought to their premises

Depends on the local laws. Where I live, they can either deal with it, or provide a secured storage space for the duration of the visit.

Either way, if a corporation wants their employees to use a device, they are obliged to make one available. Surrendering your private equipment to their management makes it not yours anymore.