Asus PCE-AC68 network force onto 802.11ac - How?

[Markus3400]

I have this terribly annoying problem. But first off, here's my setup.

Apple Airport Time Capsule (802.11ac compliant) working as router/wifi base-station
2 x Airport express extending network (only 5GHz band) - primarily for airplay streaming.
My baseline internet connection with a Cat6 cable into the motherboard on my gaming PC:

The problem is, that my gaming PC jumps onto the 802.11n network instead of the 802.11ac network. I'm guessing this is because the 5Ghz 40MHz band is so well covered by the 3 wifi senders, because i get a MCS-index value of 15 (300.0 Mbps) on my gaming rig (at 802.11n)
This is a speedtest with all my airport's setup correctly and as they should.

If i bump both Airport expresses down to the 2.4GHz band, the 5GHz 80MHz band shines through giving me a lot of through put

In the ASUS software i can clearly see the 802.11ac signal, but i can't connect to it even tho the signal is pretty good.
MAC address ending with A4:85 is the 802.11ac (5GHz 80MHz band)

So the problem i have is:
How do i FORCE the PCE-AC68 network card to only go onto the 5GHz 80MHz 802.11ac connection and NOT the 802.11n ?

 

[Markus3400]

Problem has been solved 🙂

https://discussions.apple.com/thread/7059970