Does anyone know if the hAP ac² can do WiFi Access Point and WiFi bridge mode in the same time?
In case not this device then which one?

Btw, do you have any idea what is the maximum speed one can have between two devices connected over 5GHz?

Does anyone know if the hAP ac² can do WiFi Access Point and WiFi bridge mode in the same time?

Well the hAP ac² has two wireless cards, 2.4GHz and 5GHz. Are you talking about using one of the cards (2.4GHz for example) to connect to another SSID as an uplink as well as broadcast it's own network on the same card? If so MikroTik supports virtual clients and can achieve that. You can also use the 2.4GHz to bridge and the 5GHz as an access point.

I'd like to use 5GHz only

I have done the same experiment as you mentioned. The maximum throughput was reduced by half, i.e., around 120MHz something. The main 5GHz AP was connected to the AP station of the main router. I created a virtual AP (5GHz) and connected to my Macbook Pro Retina.

YH

yhfung, and what download/upload speed did you achieve?

I configured the system as per your request using the Repeater Setup Wizard.

I got the download speed 110Mbps using the same SSID as the main AP and with wired connection I got 150Mbps.

That’s nice, thank you!