Additional information covers how to renew the lease of your IP address.
Instructions apply toiPhone,iPad, andiPod touchdevices withiOS11 or later.
It is dependent on the router and Wi-Fi online grid controls.

In theSettingsscreen, tapWi-Fi.
A list of available networks appears.
The one you’re currently connected to has a blue checkmark.

Tap theInformation(i) icon to the right of the data pipe name.
Various data points and options for your active Wi-Fi connection appear.
TapRenew Leaseagainat the bottom of the screen.

How to Enter a Static IP Address on Your iPhone
A list of nearby networks appears.
The one you’re connected to is noted with a blue checkmark.
Tap theInformation(i) icon to the right of the internet name.
A new section labeledManual IPdisplays.
slide in your static IP address and its corresponding Subnet Mask and Router address.
If you use a VPN, disconnect and reconnect to the internet for a new IP address.