Maybe this is their ' new' feature , in beta testing,  for random people. Their experiment worked because you paid up 😊

haha...modem bangsawan

Fixed Private IP (eg. 121.123.149.198), you own that IP permanently and it's will be same as your Public IP (what other sees you as), because you pay for it (make it private) specifically and no one will use that IP just you alone. When you connect/disconnect from network you'll get same IP address, forever and ever. (You post something nasty online using that IP, people can track you back because you the only one who use that IP address)

Dynamic Public IP (is free) and shared between users and assigned by ISP. eg my current Dynamic Public IP rightnow is 115.164.175.165, when I disconnect from network, Digi can anyone assign again that IP to new user connected to their network. When I connect back to Digi network, I'll get different Dynamic Public IP that's available for me to use. (That's why people do bad things online, difficult to track, their ip address keeps changing)

I disconnect my connection 3 times in a row, I got 3 different IP addresses (I'm in KL right now BTW)