Sorry for my english, I'm french.

I bought a second-hand Mikrotik HAP- AC2 router on ebay to see if it could create an effective captive Portal.
I'm having the following problem:

I connect to the router's wi-fi (MikroTik) after holding down the reset button to put it in factory configuration. This allows me to use Winbox and access the settings.
If I connect via RJ45 it also works.
The problem is that as soon as this router connects to the Internet, after about 3 minutes, the Wi-Fi disconnects and the router seems to reboot.
From then on I no longer had access to the MikroTik Wi-Fi network and 2 new networks appeared. As I don't have the passwords for these new networks, I can't connect to them. The RJ45 ports are no longer responding and won't let me connect.
So I have to do a reset. If the router is not connected to the Internet, I can configure everything with WInbox. As soon as I connect it to the Internet the problem returns.
I therefore deduce that there is some kind of script that is launched as soon as the router is connected to the Internet and that is blocking the router by creating these new Wi-Fi networks and closing the RJ45 ports.
Is this possible?
How can I solve the problem?
Thanks for your help.

Patrick

Since this is about a second hand device: Netinstall might be your best option.
Then you are sure there is nothing left behind, intentionally or by accident.

Also, maybe It Is not your case, but before connecting a device to internet you should make sure to disable all services but Winbox and limit It to LAN interface(s), possibly changing its default port number.
AND add a new user, give It full powers, and a strong password and remove or disable the default admin account.
There have been reports of devices hacked/compromised in a matter of tens of seconds of direct exposure to internet.

Hello

First of all, thank you for your answers.
I installed Netinstall (7.16.1) under Windows Vista and followed the procedure to reset my router to factory settings.
I now have the following problem: Netinstall detects my router and when I want to select Router OS 7.16.1, Netinstall does not see it. The files do not appear.

Is Windows Vista compatible?
After downloading, is there any manipulation to the Router Os file so that it is supported?

Thanks

Vista specifically should not be an issue, there are generically some possible issues with netinstall under windows, connected to its firewall and/or - when doing it on a laptop - with services and programs installed by the manufacturer, but usually they lead to netinstall not seeing the router requests.

Leave 7.16.1 alone

Try re-installing the same version that you have now.

Particularly if you have a Ros version before 7.12. something, there is a (normal) more complex upgrade path, that probably applies to netinstall as well, you first need to update to 7.12.1, and only once you have that version installed you can go further.

Also don't forget, netinstall needs to be run in admin mode on Windows.

It's perfect. With your advice I was able to upgrade my router.
Many thanks to all of you.