Ethernet to WiFi for an Ethernet device

Hi,
I have a certain device that I communicate with using a wired IP over Ethernet interface. I have no access to the device's operating system or source code. What I'd like to do is to be able to communicate with it using WiFi, taking into account that I can't install any device drivers on my device (for example, to support a USB WiFi dongle).
What I am looking for is a device that plugs in to my device's Ethernet port and serves as a WiFi hotspot for my other devices to connect to, enabling standard IP traffic to flow between my device and a computer or a smartphone.
I'll be happy for any information on this :)

Thanks,
Jeni.