This thread deals about a different subject but I see that you are using a wireless adapter for laptop on a desktop system. It is very possible that the integration of the wireless adapter and antennas is not optimal leading to such undesired behavior. This type of integration must be validated by the respective system manufacturer.
Intel® Wi-Fi Products — Regulatory information regarding hardware installation or upgrade
We suggest contacting the system manufacturer for a list of validated adapters or using the Intel® Dual Band Wireless-AC 7260 for Desktop, which is PCIe x1 and comes with antennas.