After much struggle in changing cables, configs and ISPs trying to find out where’s the issue is the only logical conclusion is - THIS IS SHITTY WAP!
I’ve placed different ISPs with up to 300Mbit/s speeds, this AP will not go over 65Mbits on 5Ghz and over 40 on 2.4Ghz regardless of the config, ISP speed, signal interference.
Both reseller and vendor specifications clearly state up to 900Mbits.(even the wireless standard states that)
Calm down. You didn’t look at the proper data to understand. Your device is set up for 20 MHz, you did not specify the frequency even, no regulatory domain, no country.
Well the 802.11 standards set this MCS table (mcsindex.com) as theoretical maxima for the wireless communication. (This is NOT brand or device related, this is the wifi as it is designed and standardized.)
2GHz can support up to 802.11n (wifi 4) standard (yellow HT MCS), 5GHz in MT can support up to 802.11ac (wifi 5) standard (green VHT MCS)
1 spatial stream or 2 spatial streams depends on the client device. A smartphone is typical a 1 spatial stream (1 antenna) device.
As said there is no bandwidth specified, so we have 20 MHz. Your max PHY rate here is 144 and 173 Mbps, but probably only 72 and 86 Mbps.(single stream device or connection)
Overhead for 802.11 is between 60% (fast rates) and 25% (slow rates). So it is common to take half the raw interface PHY speed as data rate in 1 direction.
It’s half of this again if it is bidirectional.
So 65Mbps and 40 Mbps unidirectional is perfectly normal with this setup.
In a proper setup (cfr @erlinden above) you get 390Mbps out of the 5 GHz (80 MHz bandwidth, free channels, 2 spatial streams, 866 Mbps PHY rate.), and 80 Mbps out of the 2 GHz band (20 MHz, free channel 1,6 or 11, 2 spatial streams, 144Mbps PHY)
To investigate your real connections, act as here: it is based on the “registration” values: http://forum.mikrotik.com/t/wifi-limitations/146079/1