I am using windows 10. When I go to whatismyipaddress on chrome, it shows aaa.bbb.ccc.ddd. When I go to same ip lookup website using firefox, it shows aaa.bbb.eee.fff. The computer is connected to Tmobile 4G wireless internet. I tried the same steps connecting to my iphone hotspot and ip address are still different between two browser. What even more strange is that my phone ip completely different ip block xxx.yyy but the browser on desktop showing still same ip block aaa.bbb.

Why is this happening? How can I get the same ip on the two browsers? How can I get same ip or same ip block range as on the iphone which I am using as wifi hotspot?

try restarting browser. Expecting same ip address on two different browser.