Note Microsoft recommends that you don't disable a network adapter at the function 0 port.
When a computer starts, Windows reads the hardware MaxPayLoadSize settings from hardware registry settings.
Then, Windows calculates an optimized MaxPayLoadSize value for the PCI-E bus and the endpoint devices on this bus. In this situation, Windows chooses a maximum value that's supported by both the bus and the endpoint devices. (If MaxPayLoadSize of the bus is lower than the maximum MaxPayLoadSize value of the endpoint devices, Windows will choose the MaxPayLoadSize of the bus.)
Later, when Windows starts the bus and the endpoint devices, the optimized setting will be written into hardware registry settings for the bus and the endpoint devices.
When the function 0 port is disabled, Windows will not start the device at function 0. Therefore, the operating system cannot write the MaxPayLoadSize setting back to the function 0 device. Although the operating system does write the setting to function 1 or other ports, if the endpoint device is a ARI device, the MaxPayLoadSize setting on function 1 or other ports is ignored.
Therefore, the bus has the optimized setting, whereas the endpoint devices still have the default setting. This may trigger mismatched MaxPayLoadSize values between the bus and the endpoint devices.
When the endpoint devices are network adapters, the mismatched MaxPayLoadSize
settings will break network controller driver functions and disable all network connections.