@k3dx 

This is such a weird question.
How exactly is DDNS set up?
Are the account secrets all correct?
Confirm that the DDNS Server is working correctly?
Can you provide a screenshot to show how you know that it is using another WAN IP?

Dear @k3dx ，

k3dx wrote

It does update properly when I save the settings, but after it auto-updates in around an hour it'll be set with the wrong IP.
I check the no-ip website to see what IP is there to confirm. 
WAN has a 180.x.x.x ip, WAN/LAN1 has 112.x.x.x. 
It sets 180.x.x.x once I press save but it goes to 112.x.x.x after the auto update.

 

Thank you so much for taking the time to post the issue on TP-Link community!

To better assist you, I've created a support ticket via your registered email address, and escalated it to our support engineer to look into the issue. 

The ticket ID is TKID221201141, please check your email box and ensure the support email is well received. Thanks!

Once the issue is addressed or resolved, welcome to update this topic thread with your solution to help others who may encounter the same issue as you did.

Many thanks for your great cooperation and patience!