Yesterday I updated my hap ac2 from 7.10 to 7.11.2 via winbox quick set menu. It was kindish ok at first, a few minutes later it started lagging and went into bootloop.
I tried flash firmware using netinstall following instructions published in https://wiki.mikrotik.com/wiki/Manual:Netinstall but I was unable to get netinstall to work. I am using windows 10, I tried latest netinstall 64 bit, disabled windows firewall in Windows security, added netinstall to firewall exceptions, disabled all network adapters except one to which I connected router. I connected router to eth 1 (internet port). I also tried on another PC with 2 diferent internet cards without luck. I checked with wireshark, it looks like something is happening (see pics) but netinstall does not recognize router. Is my hAP ac2 completely broken? Please help.

If your device is the factory firmware is v6 , don't use the latest V7 netinstall to connect the router. i have this same problem like you, my RB4011 want to reflash the firmware, factory firmware is V6, I use V7 netinstall can not find my RB4011, I try to use V6 6.xx.x NETINSTALL for my RB4011 , very happy to find the device and flashing firmware.

1 you need to check the device , what version of the "FACTORY FIRMWARE", /system/routerboard/print . if you reboot looping,you try the V6 old version to try it.

2 If you are the V6 like 6.XX.X ,you need to download the old version V6 6.XX.X stable netinstall to find your device.
https://mikrotik.com/download/archive

you can try it , hope you can fix your device .

Try Netinstall 7.12beta3 Testing.
If you do not succeed, try Netinstall version 6.48.6 and make sure that your Netinstall and computer configuration fits these prerequisites: https://help.mikrotik.com/docs/display/ROS/Netinstall
It is possible to install RouterOS version 7 with Netinstall version 6.
Or try Netinstall in Linux
Check both regular and backup booters https://help.mikrotik.com/docs/display/ ... kuploaders

If your device is the factory firmware is v6 , don't use the latest V7 netinstall to connect the router. i have this same problem like you, my RB4011 want to reflash the firmware, factory firmware is V6, I use V7 netinstall can not find my RB4011, I try to use V6 6.xx.x NETINSTALL for my RB4011 , very happy to find the device and flashing firmware.

1 you need to check the device , what version of the "FACTORY FIRMWARE", /system/routerboard/print . if you reboot looping,you try the V6 old version to try it.

2 If you are the V6 like 6.XX.X ,you need to download the old version V6 6.XX.X stable netinstall to find your device.
https://mikrotik.com/download/archive

you can try it , hope you can fix your device .

I downloaded netinstall v6.48 from https://mikrotik.com/download/archive and it worked! Router is alive again. Thank you very much!!!

Make sure you bring routerboot up to the same level as ROS you are running.
Or next time you may run into the same problem.

How to do this? do you mean firmware update?

System Routerboard upgrade

It's not a must every time but if your routerboard version is too far away from ROS version, you sometimes may run into problems with netinstall.
I made it a habit to upgrade routerboard with each ROS upgrade. It will indicate a reset is needed but that step I don't do.
The next upgrade or power failure will take care of that

Edit: But it looks you already did so.

before router going into bootloop I did firmware upgrade, I always do firmware update after ROS update, but current version of netinstall didn't work, so I think the reason is somewhere else. It's very disappointing that information provided in wiki is misleading and incomplete.

Hi,

If you are doing netinstall to fix bootloop, you are probably using reset button to get it into netinstall mode.
Which will almost always be using the backup bootloader, from the factory firmware.

From the manual

Note: You can also do the previous three functions without loading the backup loader, simply push the button immediately after you apply power. You might need the assistance of another person to push the button and also plug the power supply at the same time

You might be able to get this to work...
(Otherwise V6 netinstall looks to be the go)

This note in the netinstall manual is very important and solves many netinstall issues:

Some computers have a network interface (especially USB Ethernet adapters) that tend to create an extra link flap, which is enough for Netinstall to fail to detect a device that is in Etherboot mode. In such a case you can use a switch between your device and your computer or a router in bridge mode to prevent this issue.

Netinstall uses bootp packets, which are using the same port numbers as DHCP packets. If you're using a switch between your PC and the device to be Netinstalled, ensure that the ports in the bridge are not blocked by other network devices.

If you have dhcp-snooping enabled, make sure to enable "trusted" on the bridge ports facing the Netinstall PC.

in short, try a switch

well I tried on 2 different computers, with different os, different network adapters. most recent netinstall just doesn't work.

I also managed to get the hap AC^2 working with netinstall 6.45.8
I needed to press reset for 96 seconds for the router to appear in netinstall.