EAP-TTLS (Extensible Authentication Protocol - Tunneled Transport Layer Security) is an authentication protocol that allows the use of client credentials (such as usernames and passwords) while requiring a server- side certificate. Client-side certificates are optional, making it a flexible solution for environments where deploying certificates to all clients is impractical. This method establishes a secure tunnel between the client and server, ensuring that credentials are protected during the authentication process.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Designing for Specific Applications

DHCP Option 43 is used to provide vendor-specific information to clients, such as the IP address of a Wireless LAN Controller (WLC).When lightweight access points (APs) need to discover a WLC, configuring DHCP Option 43 allows the APs to obtain the necessary information to locate and join the controller.
The CWDP-305 Official Study and Reference Guide details the use of DHCP Option 43 for AP and WLC communication.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Infrastructure Design

Co-Channel Interference (CCI) occurs when multiple APs on the same channel are heard in the same area, even at relatively low signal levels. CCI is not eliminated simply because signals are below #75 dBm. In fact, CCI is a concern even when APs are heard at levels as low as #85 dBm or lower.
From CWDP-305:
"CCI can be problematic even when the signal from neighboring APs is heard at levels between #85 dBm to
#93 dBm. Effective channel planning requires minimizing overlap of same-channel signals at or above these thresholds."
- Reference: CWDP-305 Official Study Guide, Post-Design ValidationandTroubleshooting Chapter

In Europe, the 2.4 GHz band includes channels 1 through 13, whereas in North America, channels 12 and 13 are typically not used due to regulatory restrictions.If the AP in the hotel room is operating on channel 13, a laptop configured for North American standards may not detect or connect effectively to that channel, resulting in a low Received Signal Strength Indicator (RSSI).
The CWDP-305 Official Study and Reference Guide explains:
"Client devices configured for specific regulatory domains may not support all channels available in other regions. This can lead to connectivity issues when devices encounter channels that are not permitted in their configured domain." Therefore, the most likely cause of the low RSSI is the client's inability to properly connect to the AP operating on channel 13, leading it to associate with a more distant AP on a different channel, hence the weaker signal.
Reference: CWDP-305 Official Study and Reference Guide, Chapter on Post-Design ValidationandTroubleshooting