Unknown Device

I installed a Vodafone 'Super Wi-Fi extender' the other day and since then I can see a device through it that has a MAC address of 12:22:A2: D1:0C:CD but nothing can identify who makes this device. I am also unable to find the device on my network using the reported IP address and I am not able to ping the reported address. The VF extender shows correctly with a MAC of 84:1E:A3:38:9E:B8.

I would like to know who makes it as I will be able to work out which physical device this actually is, or could it simply be something to do with the mesh?

EDIT - had to insert a space in MAC address to stop a smiley appearing instead of ": D" in the string

The IP address and MAC address are different.
You can usually look up corresponding MAC/IP addresses of remote devices by using arp - a from a cmd prompt window.
You can also find the manufacturer's OUI (Organisations Unique Identifier) from the first six digits of the MAC address, and lookup the results here:
However, there is no listed OUI for 12:22:A2. So it is either from a manually assigned MAC address or a Virtual MAC address.
Since you have a Wi-Fi extender connected to your network, then the chances are that this unknown MAC address is a virtual MAC address created by the Extender.