Sometimes your computer’s IP address can change when it connects to a network, even if you haven’t made any changes to your settings. This often happens if you leave your computer turned off or if you’ve been away from home for a while. This is expected behavior of Dynamic Host Configuration Protocol (DHCP), which most networks use. However, some people need fixed IP addresses to access their devices remotely over the Internet.
when you don't have a STATIC IP address
Your home network’s router (or other DHCP server) keeps track of how long it’s been since it assigned IP addresses to your computers. To ensure that your network doesn’t run out of IP addresses, DHCP servers set a time limit, called a lease, for how long each computer is guaranteed to keep the same address, after which the address is reassigned to the next device that connects to it.
Routers typically set a relatively short DHCP lease time, which is around 24 hours, and also allow administrators to change the default value. Shorter leases make sense on large networks with many devices connecting and disconnecting, but are generally not useful on home networks. By changing your DHCP lease time to a longer value, you increase the likelihood that each computer will retain its lease indefinitely.
Alternatively, you can set up static IP addresses on a home network with more effort instead of using DHCP. Static addressing ensures that your computer always uses the same fixed IP address, regardless of how long you are disconnected between sessions.
