it is the RF maths 😉
Radio Type b/g/n means your client is connected in 2,4Gh Band. Remember the 802.11ac has 5GHz band only.
RSSI -75dBm and SNR 24 dB means your Wi-Fi signal is very poor for the fastest MSC.
- switch off 2,4G or increase the power of the 5G transceiver at the AP
- increase a channel width up to 80 MHz
and you see your 867 if measure close to AP 🙂