Router VMG8623-T50B remote access

zd59

My ISP give me access point/router Zyxel VMG8623-T50B, Firmware Version V5.50(ACDV.0)b4_E0_20240315.

As I wish to secure it as much as possible, I run to a serious problem:
The APs HTTP/HTTPS access is possible from my LAN (needed to manage it) and ALSO from internet site (WAN). So anybody can access it by brute force guess credentials.
The configuration setup is only enabling LAN access, so WAN access should be disabled.
I append a screenshot of that config. How come WAN access is working and Remote management setting show it is disabled?
Is there a bug in a firmware, or I misunderstood something?

Help needed.

Zyxel_remote_mgmt.png