Netgear AX-12 router DHCP question.

So I have this Netgear nighthawk AX-12 RAC120v2 . And I have a DHCP question. So if I have two computers on and have mapped network drives. And say my computers ip address is 182.163.1.44 . And so I map to that Ip. Then leave the two computers on 24/7 a day are so latter the ip address changed to 182.163.1.32 (Even though both computers stayed on) why would this router change the ip address ??? Especially if the computers are left on. Why would it not re-new the same ip address and carry on ? My linksys routers would never do this. It would maintain the same IP as long as the appliances are left on. I sent this question to netgear support in August after I bought the router and did not hear back from them for two months. It took them plus 60 days to answer me. And the FAQ and web sites they provided me did not answer my question.