I just had an issue with a generic droid TV box with the free "IPTV" app Live NetTV v4.8.6 and figured out what was going on kind of by accident. But it was with the IP and not the MAC address. The app has no EPG and no server config so it is not true IPTV but does have several hundred live channels from all over.
I was giving my network devices friendly names in the Access Control section of Attached Devices in my Netgear router when I noticed one of them had the address of 5.128.58.--- (obviously not a home network address). A quick Tracert and google search indicated it is a Russian IP. Gopher.com and a google translation gave the following:
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IP address, 5.128.0.0 - 5.128.255.255 (92274688 - 92340223). Domain name, l5-128-0-0.novotelecom.ru. Result (IP), Unaccounted for
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That was kind of concerning so I blocked the device in router's Access Control and found that the TV Box lost internet connectivity. With the app closed I unblocked the device and the normal DHCP assigned address appeared after I refreshed the Attached Devices list.
Knowing that the app has some mild advertising and has to receive the live streams from somewhere, I went ahead and gave the box a friendly name in the router and saved the settings. I then fired up the app on the TV box and it and other apps worked properly. Back at the router the Russian IP appeared but with my friendly name.
This box is wireless. Another wired box with the app does not have the problem. It could be that some router / TV box combinations do not release this data automatically and might lead to confusion about the MAC.