Hello everyone
Thanks for your answers, I ask the following questions

I'm interested in how to send notifications (alerts, similar to when you connect to the access point and receive an alert in the notification bar and click on the redirection to the login page) to my users connected to my Wi-Fi network (most of the smart phones), what I did was redirect the traffic through port 80 to the web proxy during a time interval and redirect to the web page that I want to show, this web page is locally on my web server.

but this only works when the user browses and sends packets through that port.

I was seeing in the forums "how to open a URL through mikrotik" and I got this information viewtopic.php?t=129644, can you explain what is the "/ tool fetch url" ?

I attach the rules that you use for the web proxy, I hope you help them

If anyone has a better idea please tell me

I hope you can guide me, I am a newbie in these topics of mikrotik

Thank you

There is no mechanism for such messages. It can't be done. You'd need some client software in all devices to receive and display the message. (I am not saying it wouldn't be handy at times, but it does not exist.)

If you hijack http connections to your proxy you will break many things. Imagine how your IoT capable toaster is going to cope with such messages, when it is checking for firmware updates – or you aquariums thermometer when it is posting via http its reading to a cloud service. Even then, more and more connections are https these days so your attempts will be futile, you can't hijack https. That's the whole point of https.

The discussion you are referring to is for when you need to initiate a http download from within RouterOS.