Why does it keep saying "IP address unavailable when I had it online y

It sounds like there is a problem with the hotspot. I would try disabling and re-enabling the hotspot feature. If that doesn't work you may want to try rebooting or find more info.

You or someone you may know might’ve changed the hot spot ip address manually, or messed around the configuration.

For PC HotSpot;

• Windows 10; try fresh installing everything from new. (Please note that… Backups is RECOMMENDED, in case you run into an error)

For IPHONE user with access to CARRIERS HotSpot;

• iOS 10+; try disabling Wifi/Bluetooth/Airplane Mode if possible then try again, this is the same for WIN10. (Please note that updating your iOS on a new device is RECOMMENDED as it might help with most issues..)
• iOS Beta; if you are on beta mode… then you will need to speak to apple’s customer service… and they probably will send everyone with the “same issues” an update. (Please note that using HotSpot in beta is NOT RECOMMENDED as it is for people to report most bugs until new releases.)

For androids, or tablet users… i do not know any details in regard for hotspot problems.