Your customer then asks you if it would be worth the investment for him to have Ethernet cabling installed to reach each of his workstations, instead of connecting them by Wi-Fi to his network. Specifically, he wants to know if that would speed up communications for the workstations. You examine his router and find that it's using 802.11ac Wi-Fi. Would you advise him to upgrade to Ethernet? Why or why not?

It depends on several factors such as the speed required for his day to day work and the wide spread.

Explanation:

With Wi-Fi he can connect to a wide range of workstations with convenience but is slower that the Ethernet.

With the Ethernet it is faster, but needs a lot of cables to be connected.

In a nutshell there are demerits and merits of both networks but it will depend on the speed and convenience the customer wants.

Answer: 802.11 ac WiFi is reasonable at the advantage to Ethernet

Explanation:

Contrasting the Pros and Cons of the two transfers.

PROS of 802.11ac Wi-Fi

Fastest maximum speed and best signal range: on par with standard wired connections

CONS OF 802.11ac Wi-Fi

Most expensive to implement; performance improvements only noticeable in high-bandwidth applications

Advantages of Ethernet:

To form an Ethernet, we do not need much cost. It is relatively inexpensive; all the node have the same privileges; It does not require any switches or hubs; Maintenance and administration are simple; robust to noise; data transfer quality is good; With a Gigabit network, users can transfer data with the speed of 1-100Gbps.

Cons of Ethernet includes:

It offers a nondeterministic service; It does not hold good for real-time applications as it requires deterministic service; As the network cannot set priority for the packets, it is not suitable for a client-server architecture; In an interactive application, data is very small and need quick data transfer; In ethernet, there is a limit of the minimum size of the frame to 46B. The result of that, it is not a good choice for interactive applications; If you are using it for interactive applications, you have to feed dummy data to make the frame size 46B which is mandatory; Not suitable for traffic-intensive applications; It provides connectionless communication over the network; After receiving a packet, the receiver doesn't send any acknowledge; If the is any problem it is difficult to troubleshoot.

On outlining the above it is better to stick with the WIFI.