Single RG-AP820-L(V3) configured for captive portal do not work

Topology:
ISP Router /No Firewal nabled) - LAN port - PoE Injector - RG-AP820-L(V3)
Action 1:
AP Registered and in sync in Ruijie Cloud project
Configures through Ruijie Cloud:
Created SSID bridged, no auth, tested internet access Ok
Created Captive portal Test, add SSID, tested in mobile: Error message: "Failed to find thenetwork"
Action 2:
Create new SSID Test 2
Delete captive portal, create a new one, default values
Test mobile: Same message.
Notes:
No gateway in the network, AP upgraded to latest available version.
Please advise

Hi, LuisGuembes
The Error message: "Failed to find the network" can be caused by 3 possible reasons:
1. Incorrect DNS resolution:
Please ping portal-eu.ruijienetworks.com on the user device when connected to WiFi and check whether the IP address resolved is 18.199.19.66.
If the domain name is resolved to an incorrect IP address, please try changing the user's DNS server to 8.8.8.8 and make sure the user is not connected to a VPN.
2. Incorrect portal configuration:
If an incorrect captive portal configuration is delivered to the AP, it will fail to load the portal page.
Please check the running configuration of the AP and verify whether the URL under the web-auth section is http://portal-eu.ruijienetworks.com/auth/wifidogAuth.
If not, please try to deliver the captive portal configuration again.
3. Occasionally the captive portal policy is not synced to the portal server successfully. In this case, please delete the current policy and create a new one.
Please let me know if the issue can be resolved with the steps mentioned. If the problem persists, please help to collect the result of the AP's running configuration as well as the captive portal policy and talk with me again.
I would be glad to help you in the Community.

Best regards,
Sophia