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R750 with ZD1200 slow throughput on Laptop with good RSSI and SNR

New Contributor II

We recently switched to four R750 AP's in our office, where we have existing R600 AP's (3 now in use) in an office with 450+ clients.

The R750 clients (laptops) are experiencing slow throughput 1-4 Mbps download; signal RSSI and SNR are good and stable.  No reports of slow throughput with clients connected to R600 AP.

One example the laptop is within line of sight of the AP (R750 with 100+ clients) about 10 meters away

  • signal RSSI and SNR are good to excellent (-65 to -72 RSSI and 28-30 SNR)
  • throughput is slow using the speed flex test laptop to ZD 2-5 Mbps
  • Speed flex AP to ZD is consistent 900+ Mbps to 1Gbps
  • Ping times laptop to AP and DG is triple to quad digit TTL

When the wireless card is toggled off and on the throughput is back to normal 400Mbps + on speed flex

(wireless card has been updated to latest driver and roaming aggressiveness is set to Medium- High)

The throughput will become slow again over time.

I've also notice the clients sitting immediately under the same R750 AP do not experience slow throughput.

Could this be the same issue as the AP must have PoH/uPoE to function properly?

Is there a configuration that is throttling the throughput of some clients and not others based on the proximity or signal strength of their connection?

Are there additional trouble shooting steps that can be done to find the root cause?

ZD firmware ver build 98

Self healing disabled

Back ground scan every 150 sec

AP's TX adjusted manually 

Only 5Ghz (80Mhz channel) enabled

R750 using 802.3at POE power injectors


New Contributor II


All the R750 AP's are powered with 60 watt 802.3bt POE power injectors per the power limitations page -

Still having slow throughput issues with some clients.  Recent testing experiencing slow throughput even when directly under the AP.

Is there a preferred firmware version on the ZD1200 for R750 AP's?

Any suggestions or insight would be much appreciated.

I am having the same problem. 


ZD1200 FIRMWARE 10.3.1 build 45

Only getting about 250 mbs connection rate.

Hi @shawn_williams_ 

Is this happening on all the clients and with all the AP models?
What is the AP model you have faced the issue on?
When the client is connected to the SSID, can you check the below details and let us know:
1. Do the Speed flex test (on android or IOS) from the app (app can be downloaded from playstore) which will tell the speed between the AP and client.
2. On the clients (example android) go to SSID details, and check the speed negotiated. Let me know the details.
3. What is the RSSI and SNR value showing on the controller GUI for this client?