Connection refused from a HP Elitebook 820 G4 to hAP AC2 5GHZ

I have a strange problem as follows:
I have an hAP ac2 as access point that works flawlessly for the last 3 years with various devices connected on both 2.4 GHz and 5GHz wifis.
I bought a used HP Elitebook 820 G4 a few days ago and while it is connected fine at 2.4GHz when i trying to connect to 5GHz the message is “Cannot connect to this network”. Tried to forget the network but the problem persists. The laptop can connect just fine to other 5GHz wifis without any problem.
Installed the drivers for the wifi card, no change…
No fancy setup for my hAPac2… nothing special
No problem with this hAP ac2 with a bunch of other devices both old and new… never had a problem…

Any ideas how can i troubleshoot it further?

What frequency is your hAP on? Some WiFi chip sets can’t connect to the higher frequencies. The Realtek in my cheap Android tablet for example.