Upgrading access points (APs) from 802.11n to 802.11ac can offer higher throughput and improved performance. However, to realize these benefits, client devices must also support the newer standard. If the clients remain on 802.11n, they cannot leverage the advanced features of 802.11ac, such as wider channel bandwidths, higher modulation schemes, and increased spatial streams.
The CWDP-305 Official Study and Reference Guide emphasizes the importance of considering client capabilities during WLAN upgrades:
"When upgrading a WLAN, it's essential to assess both infrastructure and client devices. Upgrading APs without corresponding client support may not yield the expected performance improvements." Therefore, in this scenario, the most likely cause of the unchanged throughput is that the client devices were not upgraded to support 802.11ac.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

CAPWAP and DTLS are the type of standards-based encryption used by office extension APs for the traffic tunnel. Office extension APs are wireless access points that can be deployed in remote locations and connect to a central wireless controller via a secure tunnel over the Internet. CAPWAP is the Control and Provisioning of Wireless Access Points protocol, which defines how the wireless controller and the office extension APs communicate and exchange control and data messages. DTLS is the Datagram Transport Layer Security protocol, which provides encryption and authentication for the CAPWAP tunnel. DTLS is based on TLS, but it uses UDP instead of TCP as the transport layer protocol, which makes it more suitable for real-time applications. DTLS protects the CAPWAP tunnel from eavesdropping, tampering, and replay attacks, and ensures the confidentiality and integrity of the wireless traffic. References: CWNP, CWDP Certified Wireless Design Professional Official Study Guide, Configure OEAP and RLAN on Catalyst 9800 WLC, Hardening Microsoft 365, Office 2021, Office 2019 and Office 2016

For 802.3bz MultiGig Ethernet, which supports speeds of 2.5 Gbps and 5 Gbps over twisted-pair cabling, the recommended cabling standards vary based on the distance:
Cat-5e: Suitable for 2.5 Gbps up to 100 meters; 5 Gbps up to 55 meters
Cat-6: Suitable for 5 Gbps up to 55 meters
Cat-6a: Suitable for 10 Gbps up to 100 meters
Given that some cable runs will exceed 55 meters, Cat-6a is the most appropriate choice to ensure reliable MultiGig performance over longer distances.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

In WLAN operations, two primary scanning methods are employed by client devices to discover available wireless networks:
Active Scanning:The client device actively sends out probe request frames on various channels. Access Points (APs) that receive these requests respond with probe response frames, providing information about the network. This method allows clients to discover networks even if they are not broadcasting their SSIDs.
Passive Scanning:The client device listens for beacon frames that are periodically transmitted by APs. These beacons contain information about the network, such as SSID, supported data rates, and security protocols.
Passive scanning is less intrusive and does not generate additional traffic, but it may take longer to discover networks, especially if the beacon interval is lengthy.
Understanding these scanning methods is crucial for network design and troubleshooting, as they impact how quickly and efficiently clients can connect to available networks.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on ProtocolandSpectrum Analysis

Channels 116-124 in the 5 GHz band fall under the Dynamic Frequency Selection (DFS) range. These channels are shared with radar systems, such as those used by airports. When radar activity is detected, Access Points (APs) operating on DFS channels must vacate the channel, leading to potential disruptions in service. In environments near airports, it's advisable to avoid using DFS channels to prevent such interruptions, ensuring a stable and reliable wireless experience for voice devices.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Wireless Design Process