5G Fixed Wireless & Wi-Fi Diagnostic + Interference Survey

Use this expanded question sheet before you troubleshoot. It collects everything you need for a 5G router (fixed wireless access or hotspot) and the local Wi-Fi environment—with extra depth on wireless interference.

1) Site & Contact

  • Date: __________ Tech/Contact: __________ Location: __________
  • Use case (POS / Work / Streaming / Cameras / Other): __________________

2) Physical Setup & Power

  • Router placement: ☐ Window-facing ☐ Interior ☐ Enclosure/closet ☐ Near metal/brick
  • Height from floor: ______ ft/m Distance to main devices: ______ ft/m
  • Antennas: ☐ Internal ☐ External (model/gain: ______ dBi) Aimed at tower? ☐ Yes ☐ No
  • Ventilation: ☐ Clear ☐ Warm ☐ Overheating suspected
  • Power: ☐ Wall outlet ☐ Surge bar ☐ UPS Any brownouts? ☐ Yes ☐ No

3) Cellular (5G/LTE) Link Health

  • Carrier: __________ Plan throttling/deprioritization? ☐ Yes ☐ No ☐ Unknown
  • Current RAT: ☐ 5G mmWave ☐ 5G mid-band/C-band ☐ 5G low-band ☐ LTE
  • Band/NR-ARFCN (if shown): __________ Carrier aggregation active? ☐ Yes ☐ No
  • Signal metrics (from router UI/app):
    • RSRP: ______ dBm RSRQ: ______ dB SINR: ______ dB (Good targets: RSRP ≥ −90 dBm, RSRQ ≥ −10 dB, SINR ≥ 10–15 dB)
  • SIM seated & APN correct? ☐ Yes ☐ No Tower changes recently? ☐ Yes ☐ No
  • External antenna cable length/type: __________ Line-of-sight? ☐ Full ☐ Partial ☐ None

4) LAN/Wi-Fi Topology

  • Router model/firmware: __________________ Last update: //____
  • Additional APs/mesh/extenders? ☐ None ☐ Mesh ☐ Repeater ☐ Powerline
  • Backhaul type (if mesh): ☐ Wireless ☐ Ethernet
  • VLAN/Guest network isolation for visitors/IoT? ☐ Yes ☐ No
  • QoS/SQM (fq_codel/cake) on WAN? ☐ Enabled ☐ Disabled ☐ Unknown

5) SSIDs, Security & Client Mix

  • Bands in use: ☐ 2.4 GHz ☐ 5 GHz ☐ 6 GHz (6E) Separate SSIDs per band? ☐ Yes ☐ No
  • Security: ☐ WPA3 ☐ WPA2-AES ☐ Other: ______ WPS disabled? ☐ Yes ☐ No
  • Channel width set:
    • 2.4 GHz: ☐ 20 MHz (recommended) ☐ 40 MHz
    • 5 GHz: ☐ 20 ☐ 40 ☐ 80 ☐ 160 (DFS?)
    • 6 GHz: ☐ 20 ☐ 40 ☐ 80 ☐ 160
  • Client count (peak): Phones: ___ Laptops: ___ TVs: ___ Cameras: ___ IoT: ___ POS: ___
  • Old clients present (802.11b/g or 2.4-only IoT)? ☐ Yes ☐ No

6) Performance Measurements

(Run tests both off-peak and peak hours. Record gateway, WAN, and app-server latencies.)

  • Idle ping to router/gateway: ______ ms Jitter: ______ ms
  • Ping to ISP DNS: ______ ms Packet loss: ______ %
  • Ping to app/server (e.g., payment gateway): ______ ms Loss: ______ %
  • Under download load: Ping: ______ ms Jitter: ______ ms
  • Under upload load (video call/file send): Ping: ______ ms Jitter: ______ ms
  • Speed (down/up): ______ / ______ Mbps
  • Bufferbloat grade (Waveform/DSLReports): ______
  • LAN test (iperf or file copy) throughput: ______ Mbps Retries: ______ %

Interpretation quick notes

  • Idle vs Download/Upload Ping: Idle shows baseline path; spikes under load indicate bufferbloat or scheduler/QoS issues.
  • Packet loss >1% or jitter >30 ms will break real-time apps (calls/POS auths).

7) Wi-Fi Channeling & Congestion

  • Current channels: 2.4 GHz: ____ (Use only 1/6/11 in most regions)
    5 GHz: ____ (DFS in use? ☐ Yes ☐ No) 6 GHz: ____
  • Auto-channel enabled? ☐ Yes ☐ No Manual reason: __________________
  • Channel utilization (from router/analyzer):
    • 2.4 GHz: ______ % 5 GHz: ______ % 6 GHz: ______ %
  • Airtime usage breakdown (if available): Beacons/Management ______ % Data ______ % Retries ______ %
  • Noise floor (if shown): 2.4: ______ dBm 5: ______ dBm 6: ______ dBm

8) Wireless Interference Deep-Dive

A) Co-Channel & Adjacent-Channel

  • Neighbor APs on same channel? ☐ Yes ☐ No Count: ______
  • Adjacent-channel overlap (wide channels stepping on others)? ☐ Yes ☐ No
  • Hidden-node symptoms (good RSSI, high retries/low throughput)? ☐ Yes ☐ No

B) Non-Wi-Fi Interferers (2.4 GHz especially)

  • Microwaves nearby? ☐ Yes ☐ No (when used, Wi-Fi drops?) ☐ Yes ☐ No
  • Cordless/DECT phones? ☐ Yes ☐ No
  • Bluetooth hubs/beacons? ☐ Many ☐ Few ☐ None
  • Zigbee/Thread (smart home/IoT) density: ☐ High ☐ Medium ☐ Low
  • Baby monitors/wireless cameras/analog senders? ☐ Yes ☐ No
  • Fluorescent lights/ballasts or old power supplies near AP? ☐ Yes ☐ No

C) 5 GHz/6 GHz Specifics

  • DFS radar events logged? ☐ Yes ☐ No Auto-switches observed? ☐ Yes ☐ No
  • 160 MHz channels used (fragile in busy spaces)? ☐ Yes ☐ No

D) Structural/Material Attenuation

  • Low-E/metal-coated windows between router and clients? ☐ Yes ☐ No
  • Refrigerators/freezers/elevators between? ☐ Yes ☐ No
  • Concrete/brick/metal walls or racks? ☐ Yes ☐ No

E) Client Behavior & Airtime Fairness

  • A few far/slow clients dragging down airtime? ☐ Yes ☐ No
  • Multi-user MIMO/OFDMA supported by clients? ☐ Yes ☐ No ☐ Mixed
  • Roaming issues (sticky clients not handing off)? ☐ Yes ☐ No
  • Band-steering enabled? ☐ Yes ☐ No Impact: __________________

9) Signal Quality at Problem Spots

  • RSSI/SNR at device location(s):
    • Device A: RSSI ______ dBm / SNR ______ dB
    • Device B: RSSI ______ dBm / SNR ______ dB
  • Target guidance: SNR ≥ 25 dB for stable high MCS; RSSI ≥ −65 dBm preferred for 5 GHz/6 GHz work devices.

10) Router/AP Radio Settings

  • Transmit power: ☐ Low ☐ Medium ☐ High (Avoid “Max” if it unbalances roam)
  • Min data rate (disable legacy rates like 1–6 Mbps)? ☐ Yes ☐ No
  • MU-MIMO/OFDMA enabled? ☐ Yes ☐ No
  • DTIM/Beacon interval defaults? ☐ Yes ☐ No Custom values: __________
  • IGMP snooping/multicast optimization (for IPTV/cams)? ☐ Enabled ☐ Disabled

11) Interference Mitigation Checklist (Action Plan)

  • 2.4 GHz: lock to 20 MHz; use 1/6/11 only. ☐ Done
  • 5 GHz: prefer 40/80 MHz; avoid 160 MHz in busy areas. ☐ Done
  • Move AP/router higher & open, away from appliances/metal. ☐ Done
  • Separate SSIDs per band; steer capable clients to 5/6 GHz. ☐ Done
  • Reduce Tx power a notch if clients “stick” to distant AP. ☐ Done
  • Enable SQM (cake/fq_codel) on WAN to fix bufferbloat. ☐ Done
  • Reposition/aim external cellular antennas; shorten coax runs. ☐ Done
  • Try alternate 5G band/carrier aggregation profile (if supported). ☐ Done
  • Schedule heavy backups/updates off-peak. ☐ Done
  • Replace legacy clients (2.4-only, 802.11b/g) or isolate on IoT SSID. ☐ Done

12) Third-Party Dependencies

  • App/payment gateway status pages checked? ☐ Yes ☐ No
  • Latency path compared (LAN → WAN → App)? ☐ Yes ☐ No
  • VPN in use? Test without VPN: Latency ______ ms Loss ______ % ☐ Improved ☐ No change

13) Validation After Fixes

  • New idle/download/upload pings: ___ / ___ / ___ ms
  • New jitter/loss: ___ ms / ___ %
  • Throughput stable? ☐ Yes ☐ No Retries reduced? ☐ Yes ☐ No
  • Problem use-case (POS/Zoom/Stream) now passes? ☐ Yes ☐ No Notes: __________

Quick Reference: Good/Okay/Bad Targets

  • RSSI: ≥ −65 dBm (good), −75 to −66 (okay), < −75 (weak)
  • SNR: ≥ 25 dB (good), 15–24 (borderline), < 15 (poor)
  • Loss: < 1% good; 1–2% borderline; > 2% problematic
  • Jitter: < 20 ms good; 20–30 ms okay; > 30 ms problematic
  • Bufferbloat: A/B good; C/D/E fix with SQM