Problems with the captive portal mt300n-v2 firmware 3.025

I need your help to find out what is the reason that I don’t work the captive portal in my mt300n-v2 with firmware 3.025. First active network guest, then when I try to activate the captive portal on the interface virtual guest are not active, says to me network not available. I have my router in repeater mode via WiFi.

sorry to reply you so late:
First, you need to make sure that the route is properly connected to the Internet (preferably disable DNS Rebinding Attack Protection, Connect to Captive Portal - GL.iNet Docs)
Second, you need to open the guest network first (I see that you have already done it)

Thanks for comment, I have disable DNS rebinding attack protection. Is it necessary to have a active Internet connection to work the captive portal ?. I can’t use the captive portal on a local network ?.

Yes, your device needs to be able to access the external network, otherwise the domain name cannot be resolved.

I need a captive portal that works on a local network, what do you suggest?

The jump URL uses the ip address, which can be popped up to the authentication page. If you can guarantee that the jump after authentication is also possible to access the LAN, you can use the LAN.