Persistent Backdoor QuestioN

Hello guys,

Rookie here, so i was watching OTW series, and i have a couple of questions,

lets imagine that i want to compromise some machines, and i want to have a persistent acess to it, in a WAN and LAN environment, since when you make a payload the LHOST cant be changed after being executed in the victim machine so how can I resolve this problem, and other thing in a WAN environment i dont have a fixed public IP so how can i workarround this, since my ip changes.

Ty for your time