I had the same IP address for the entire 3 years I lived in an apartment. Even telling my router to release and renew the IP would still give me the same IP. Only when I moved to a new house (and still used the same ISP) did my IP change.
You don't need a tool to change your MAC address. You can do it from the Control Panel.
And as another commenter said, this would only change my local IP (192.168.254.x) IP, not the WAN IP (50.39.x.x). I would need to change my router's MAC address, since that's the only MAC address my ISP sees. And depending on my ISP's DHCP configuration, I still might not get a different IP. I might even make it unable to get an IP at all.
I did this many times back when I just had a plain cable modem, not router or anything. I havent tested since I switched to a Modem Router combo, I would suspect it wont work under that setup.
But yes, my original point stands. I can run the tool, change my network cards MAC, restart the Modem, and I get a new public IP address. Ive been doing this for years to bypass IP blocks.
Ahh, that explains a bit: let me guess, your modem had a single Ethernet port on it, which you were running directly to your computer?
That means the modem was cloning your device's MAC address onto its own WAN interface. Which is... weird, but would have had some kind of logical motivation.
Maybe it meant the modem vendor didn't have to maintain their own MAC registration ("just copy the device's!"), or maybe it was an ISP "what kinds of devices are our customers using?" kind of thing (the majority of results would have been routers, not single devices). Or maybe this is normal for cable modems (never used cable myself, just ADSL2+).
I had the same IP address for the entire 3 years I lived in an apartment. Even telling my router to release and renew the IP would still give me the same IP. Only when I moved to a new house (and still used the same ISP) did my IP change.