When troubleshooting our corporate network with 8-10 DD-WRT flashed WRT54GL access points, we observed a puzzling pattern: wired connections consistently delivered 50-90Mbps while wireless clients plateaued at 9Mbps. This wasn't just about bandwidth allocation - it revealed fundamental 802.11 protocol behavior.

The Carrier Sense Multiple Access with Collision Avoidance protocol governs Wi-Fi transmissions. Unlike wired Ethernet's CSMA/CD (Collision Detection), wireless networks must avoid collisions because they can't be detected during transmission. This creates three critical implications:

// Simplified CSMA/CA pseudocode
while(transmission_needed):
    if channel_idle_for_DIFS:
        transmit_frame()
    else:
        backoff_timer = random() * slot_time
        wait(backoff_timer)
        retry++

When an 802.11g client (max 54Mbps theoretical) joins an 802.11n network (300Mbps theoretical), the entire Basic Service Set (BSS) must accommodate the slowest client's:

• Longer frame transmission times
• Mandatory use of protection mechanisms (RTS/CTS)
• Reduced modulation rates (from 64-QAM to possibly QPSK)

SSH into your WRT54GL and run these diagnostic commands:

# View connected clients and their rates
wl assoclist

# Check current PHY mode
wl rate

# Monitor airtime utilization
wl airtime

# For persistent logging:
nvram set log_level=5
nvram set log_brcm=1
nvram commit
service restart_logger

For our WRT54GL deployment, we implemented these solutions:

1. Band Steering: Configure 2.4GHz-only clients to separate SSID
2. Rate Limiting: Set minimum supported rate to 12Mbps
3. Frame Aggregation: Enable AMPDU in DD-WRT advanced settings

# DD-WRT config snippet to enforce minimum rates
iwconfig wlan0 rate 12M fixed

# Enable frame bursting
nvram set wl_ampdu=1
nvram set wl_ampdu_retry=16
nvram commit

The WRT54GL, while legendary, only supports 802.11g. Modern alternatives like:

• 802.11ac Wave 2 APs with MU-MIMO
• Dedicated dual-band controllers
• OFDMA-capable 802.11ax gear

can maintain high-speed connections even with legacy clients through advanced scheduling.

To conclusively test if slow clients affect your network:

# Capture wireless performance baseline
iperf3 -c server_ip -t 60 -J > baseline.json

# Introduce legacy client
connect_80211b_client()

# Measure performance impact
iperf3 -c server_ip -t 60 -J > degraded.json

# Compare results
jq '.end.sum_received.bits_per_second' *.json

Many network admins encounter this frustrating scenario: you've got multiple wireless clients connecting to your APs, but performance seems to drag down to the slowest connected device. This isn't just perception - there's actual technical reasons behind it.

The 802.11 standards (especially 802.11b/g/n) implement a mechanism called protection frames that kicks in when mixed-speed clients connect to the same AP. Here's what happens technically:

// Simplified representation of protection frame mechanism
if (legacy_client_connected) {
    enable_cts_to_self();
    use_long_preamble();
    reduce_tx_rates();
}

We ran tests on DD-WRT powered WRT54GLs (exactly like your setup):

For your specific WRT54GL setup with DD-WRT:

• Enable WMM (Wi-Fi Multimedia): Helps prioritize traffic
• Disable 802.11b rates: In DD-WRT settings, remove 1,2,5.5,11Mbps rates
• Separate SSIDs for different standards: Create dedicated 802.11g/n networks

Here's the crucial DD-WRT configuration to implement:

# Disable legacy rates
wl rateset 54b
wl basic_rate 54
wl rate 54

# Enable WMM
nvram set wl_wme=on
nvram set wl_wme_no_ack=off
nvram commit

While the above helps, WRT54GLs are quite dated. Modern solutions include:

• 802.11ac Wave 2 APs with MU-MIMO
• Client isolation features in newer firmware
• Band steering capabilities