Libreelec frozen on Kodi Leia logo

Changing a provider should not change your local network addresses, unless you also have a new/different router.

In a decent router you should be able to change the DHCP pool from which all your local network devices get their IP addresses.

In a decent router you should also be able to fixate certain IP addresses for selected network devices, which is recommended for (for example) NAS devices and other servers.

In your router's summary or other info, you should also see the (new) IP address of your NAS. Once you know the new IP address, you can change it in Kodi's advancedsettings.xml file, as you previously did for connecting to the shared library. With that new IP address, Kodi should work again.