If they let the domain expire, the DNS (like the internet phonebook) updates tend to depend on your ISP (internet provider), and some can take up to a week to refresh. You can force an update with
ipconfig /flushdns and then
ipconfig /registerdns from an elevated command prompt on Windows. Or, to keep it simple you can first try rebooting your PC (may not work). On mobile, your carrier manages your DNS so it is kind of out of your hands.
Here is a tutorial on how to
ipconfig /flushdns, just do the same thing for
ipconfig /registerdns after doing the flush -
https://www.bleepingcomputer.com/tutorials/clear-flush-dns-cache-in-windows/