Information about supported wireless speeds.
Unable to find the speed when an 802.11ax device connects to 802.11ac router, the 5 GHz specification of the wireless router says that it can reach 1732 Mbps. It is reaching 866 Mbps only.
When a Wi-Fi 6 (802.11ax) device connects to a Wi-Fi 5 (802.11ac) wireless router, the connection will default to the capabilities of the 802.11ac standard.
For 802.11ac, the maximum speed can be up to 1.73Gbps (this is theoretical.) However, real-world speeds are usually lower due to various factors such as interference, network congestion, router/modem configuration, motherboard/PC capabilities, antennas, and signal strength.
The best approach is to consult the motherboard/PC and router manufacturers to verify the proper settings.