Are the rtl8814au drivers updated? I did a custom build and the custom drivers seem to get 25% more throughput.
I did a make from this guide Edimax guide: How to install EW-7833UAC in Linux running kernel higher than v4.4
The driver has updates for:
{USB_DEVICE(USB_VENDER_ID_REALTEK, 0x8813),.driver_info = RTL8814A},
{USB_DEVICE(0x2001, 0x331a), .driver_info = RTL8814A}, /* D-Link - D-Link */
{USB_DEVICE(0x0b05, 0x1817), .driver_info = RTL8814A}, /* ASUS - ASUSTeK */
{USB_DEVICE(0x0b05, 0x1852), .driver_info = RTL8814A}, /* ASUS - ASUSTeK */
{USB_DEVICE(0x0b05, 0x1853), .driver_info = RTL8814A}, /* ASUS - ASUSTeK */
{USB_DEVICE(0x056E, 0x400B), .driver_info = RTL8814A}, /* ELECOM - ELECOM */
{USB_DEVICE(0x056E, 0x400D), .driver_info = RTL8814A}, /* ELECOM - ELECOM */
{USB_DEVICE(0x7392, 0xA833), .driver_info = RTL8814A}, /* Edimax - Edimax */
{USB_DEVICE(0x7392, 0xA834), .driver_info = RTL8814A}, /* Edimax - Edimax */
{USB_DEVICE(0x20f4, 0x809a), .driver_info = RTL8814A}, /* TRENDnet - TRENDnet */
{USB_DEVICE(0x20f4, 0x809b), .driver_info = RTL8814A}, /* TRENDnet TEW-809UB */
{USB_DEVICE(0x2357, 0x0106), .driver_info = RTL8814A}, /* TP-LINK Archer T9UH */
{USB_DEVICE(0x0846, 0x9054), .driver_info = RTL8814A}, /* Netgear A7000 */