Hello, friend!
Based on the information you describe, your demands can be fulfilled.
The routing mode is set for the HG8245Q2, and the bridging mode is set for the AX3.
HG8245Q2:
Login HG8245Q2 WebUI.
In the navigation tree on the left, choose WAN > WAN Configuration. In the dialog box that is displayed, set Mode to Route WAN.
The following figure shows the configuration of the AX3.

Thanks!