@2jAREK; Your screenshots are not giving good info. What are the RTS/CTS settings in both 802.11n or 802.11ac? What are signal strengths of the clients.
Did your readup on 802.11ac IEEE protocol standard? Hidden node is no longer an issue since it is the AP that hands out airtime to associated devices, unlike in802.11'n' protocol.
I run many AP's in 802.11ac mode and it almost always outperforms 802.11n devices, especial when there is lots of interference or units cannot 'see' eachother. ("Hidden node").
Another feature of 802.11 ac is the 80Mhz wide band. You can now use up to 4 AP's in the same band but make sure each has another 'pilot' channel. Now devices that 'hear' another AP in de band as what they should be listening too it will not use that 20Mhz channel for that CPE. Now this CPE will have less capacity but still 40Mhz bandwidth or in the worse case scenario 20Mhz.
Even in this worse case scenario, given that the signal is good enough you could still get higher MCS then possible under 'n' protocol
Because many CPE's now can work with 40 or even 80Mhz wide channel you create much more spectrum space for each AP to make use for sending and receiving data so the data demands from clients gets processed much faster then in 20Mhz thus much more time to deal with 'talking' to other clients.
On a mild to moderate used network (and I use up to 35-40 clients per AP!) this works perfect. NV2 can never give me the same results.
In NV2 ping times are only slightly lower but capacity is less then half and much more interference issues.....
But it needs a lot of fine tuning.
- Good to high signals. Use the best directional client antenna you can get for a reasonable price. (LHG, DISC)
- Always try to separate channel use (Competition!) as much as possible for AP's.
- Make wifi scan (and if possible spectral scan) from client to see where his biggest interferers come from and try to adjust things...
- Set RTS/CTS to always work and set "cts to self" on AP
- set Guard Interval to 'long' (more stable links at the expense of a little bit less throughput)
-set Preamble to long (more stable links at the expense of a little bit less throughput)
- Enable ANI both on client and AP
- Hw retries = 7 or lower.
- Choose your frequency carefully. 5Mhz up or down, or Ceee instead of eCee or eeeC can make a lot of difference....
I sometimes need a full day to find the best setting for an AP.... it means a lot of tests, tryouts and changes....
And sometimes I find the next week I have to start all over again because some friendly competitor decided to 'shruck' his bands too close to mine.....
And still sometimes NV2 is better or even nstreme. I have 80% of my AP's use plain 802.11ac and the rest is either nstreme or NV2.
Even on backhauls I mostly use 802.11ac now, mikrotik links doing 300Mbps over several km's are possible.....