E750: VPNs, captive portals and WISP

Hi, I was wondering that when I have my Mullvad WireGuard VPN on, the captive portal for public wifi doesn’t pop up when I use WISP. Is there a proper way of getting it working? I also have Adblock force DNS on but DNS rebinding protection off.

My experience with AR750S (not E750).

I normally turn off - VPN client/server and all settings under Custom DNS Server before connecting to any public wifi.
Upon connected to the public wifi, the router will disconnect and reconnect again.

After that the public wifi captive portal will prompt.

Upon entering all the necessary and secure a session, I then return to change my DNS setting and activate VPN.

Troublesome, but work most of the time.

Now you have to do this manually https://docs.gl-inet.com/en/3/troubleshooting/captive_portal/

Checkout this post What does it mean "portal detect" firmwares?
about captive portal detection.