cellphone's 4G network as internet connection
That doesn't sound like the best of ideas, but I don't think anyone will be able to help you unless they know a lot about phone tethering. I have to imagine that is the cause of your IP not working with EQBC properly. You could try using a loopback IP address like 127.0.0.1 and maybe that will work, but I have literally no info on how phone networks act as modems
I wouldn't even be comfortable gaming on a wireless connection to an actual modem 20 feet from me. If you want to post a screencap of the ipconfig, it'll probably help get an answer.