Not sure if this would help.
But to be honest, I think you should be looking for a DDNS service ...
alanh999 發表於 2019-2-9 16:55 
Wi-Fi: Changing DNS details
Enter the Settings app on your iOS device, and select Wi-Fi. Tap the small "i" icon next to the name of the network that needs the DNS server details changed, scroll down, and tap Configure DNS. |