I currently have a hAP ac3 with RouterOS 6.49.17. I’m considering upgrading to 7.12 or 7.13 to test wifiwave2 (7.12) or the wifi package in 7.13, to see if I can get better speed and performance on my Wi-Fi network.
My suggestions:
Before doing step #2, do a textual export of config, it can prove a valuable aide when configuring anew. Won’t help much with wifi though.
Keep in mind for netinstall: on 7.13+ you need wireless or wifi-qcom-ac package additionally to main package.
Why not? I’ve heard that some people experience or have achieved better Wi-Fi performance through wifiwave2.
He meant old wifi config won’t help since in new versions there’s new wifi package which differs in configuration, and you should do it from scratch
So, if I install 7.13 or later, do I need to add the wifi-qcom-ac from the extra package to get wifiwave2? If I don’t, will I just get the regular wireless?
If you install 7.13 or later, it comes without any wireless/wifi drivers. So you have to install one extra package, either wireless (legacy stuff) or wifi-qcom-ac (new driver, which is development of wifiwave2).
Thank you
One last question: Do I download and use the Netinstall version for RouterOS 6 or the one for 7 when upgrading from 6.49.17 to 7.x?
There are two when I look under the download section. One under v6 and one under v7.
Use netinstall for 7.15.3 (or whichever ROS version you decide to start with). Don’t mess with netinstalling v6, upgrading from v6 to v7 leaves (hidden) v6 setup on device which consumes (precious) space.
When doing netinstall, select both routeros and wifi-qcom-ac packages in the same step, this avoids some possible gotchas later on (such as not applying default config for wifi).
After you get into ROS after netinstall, don’t forget to upgrade routerboot (the “BIOS” part) in /system/routerboot …
This step?
https://wiki.mikrotik.com/wiki/File:Netinstall_Win10_15.png
Check: RouterOS and wifi-qcom-ac
Yes
Thank you 
All done now. My HAP-ac3 has been reborn with fresh new powers, and the WiFi is much better, with improved signal strength and speeds.
RouterOS: 7.15.3 arm
Extra package: wifi-qcom-ac
Updated the routerboard after the netinstall
Basic vanilla settings and changes on the configuration.
I understand everyone who initially complains about the wireless network when using the old junk that came with it. Much more satisfied with the new one. We’ll see how it performs over time.