@RouterHang 

As per your description, the AX1500 LAN and the ISP modem LAN belong to two different networks, so the PCs in different networks cannot communicate with each other. You can either change your ISP modem into bridge mode or change the AX1500 into an access point.

This is the guide to configure the AX1500 into an access point:

https://www.tp-link.com/support/faq/2066/

While there will be some features cannot be used once it is in an access point mode, so you need to change your modem to bridge mode if you want all features on the AX1500:

https://www.tp-link.com/support/faq/2420/

Good day.

@Kevin_Z 

Thankyou for reply

Do you remember about my QoS problem ?

My another solution is my computer directly connect to ISP modem 

And another user connect from TP-LINK

So i can use QoS to limit all of them and also i can use all of bandwidth because i connect from ISP modem

I will try about bridge mode, but my modem is fiber optic router and they wont tell about username or password

But is there any more solution ? like static routing or something ?

@RouterHang 

If that is the case, you may check if you can still have the advanced settings on the AX1500 by switching it into an access point manually as this guide:

https://www.tp-link.com/support/faq/417/