mediumMultiple Choice
802.11ac 5 GHz Only: Why Some Devices Can't Connect
During a network upgrade, a technician installs a new 802.11ax (Wi-Fi 6) access point in a conference room. Users now report intermittent disconnections on their older laptops. What is the most likely cause?
⚠ Common exam trap
220-1201 often tests the misconception that newer Wi-Fi standards are always fully compatible with older clients, ignoring the impact of channel width and other radio settings on legacy devices.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The channel width is set too wide for older clients.
Older Wi-Fi clients that do not support 802.11ax may struggle with wide channel widths (e.g., 80 MHz or 160 MHz) because their radios are designed for narrower channels and may not properly interpret or coexist with the wider transmissions. This can cause intermittent disconnections as the AP and client negotiate incompatible channel settings. Reducing the channel width to 20 or 40 MHz typically restores stability for legacy clients.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The access point is overheating.
Why it's wrong here
An overheating access point typically exhibits symptoms such as thermal throttling, leading to a general decrease in performance for all connected devices, or complete system instability like random reboots or shutdowns. It is highly unlikely for overheating to selectively cause intermittent disconnections only for older client devices while newer laptops maintain a stable connection, as the thermal issue would affect the AP's overall operation indiscriminately.
- ✓
The channel width is set too wide for older clients.
Why this is correct
Modern Wi-Fi standards, such as 802.11ac and 802.11ax, utilize wider channel widths (e.g., 80 MHz or 160 MHz) to achieve significantly higher data throughput. Older Wi-Fi clients, often based on 802.11n or earlier, may only support narrower channels (20 MHz or 40 MHz). If the new access point is configured to exclusively use a wider channel that older clients cannot properly interpret or negotiate, these legacy devices will experience intermittent disconnections or an inability to connect, while newer, compatible devices operate normally.
- ✗
The DNS server is misconfigured.
Why it's wrong here
A misconfigured DNS server primarily affects a client's ability to resolve domain names into IP addresses, which is essential for accessing internet resources by name. While this would prevent web browsing or accessing network services, it does not directly cause the client to intermittently disconnect from the Wi-Fi access point itself. The wireless connection layer would remain stable, but applications requiring name resolution would fail to function.
- ✗
The power over Ethernet (PoE) injector is faulty.
Why it's wrong here
A faulty Power over Ethernet (PoE) injector would directly impact the power supply to the access point. This type of failure typically results in the AP either failing to power on, experiencing frequent and complete reboots, or operating erratically for all connected devices due to insufficient or unstable power delivery. Such a power-related issue would not selectively cause intermittent disconnections for only older client devices while newer ones remain unaffected, as the AP's core functionality would be compromised for everyone.
Go deeper
Related to this question
Learn chapter
BIOS and UEFI Settings
Key term
Access Point
An access point is a device that creates a wireless local area network, usually by connecting to a wired network and broadcasting a Wi-Fi signal for computers, phones, and tablets to join.
Key term
Wi-Fi
Wi-Fi is a technology that lets devices like laptops and phones connect to the internet or communicate with each other wirelessly using radio waves.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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