@ajeast 

Okay, I understand that you are experiencing significantly slower Wi-Fi download speeds compared to your upload speeds on your Deco Mesh system, even though your wired (Ethernet) connection achieves full speed. You have already tried disabling QoS, NAT, and SIP ALG, but the issue persists.

Here are some suggestions to help you accurately measure and potentially improve your Wi-Fi speed:

1. Accurate Speed Testing:
• Use https://www.speedtest.net or the Speedtest app/CLI for reliable speed tests.
• To rule out issues with your ISP or modem, connect a PC directly to your ISP modem/router and test the speed.
• For wired speed testing, connect your PC directly to the main Deco unit. Ensure all Ethernet cables are CAT5E or above, and that the modem, Deco, and PC Ethernet ports support your subscribed bandwidth.

2. Wireless Speed Testing:
• Make sure your device is connected to the nearest Deco unit and is using the high-speed Wi-Fi band (5 GHz or 6 GHz), not 2.4 GHz.
• Ensure no other devices are using high bandwidth (e.g., downloading or streaming) during your test.

3. Troubleshooting Steps to Improve Speed:
• If Ethernet speed is slower than expected, try different Ethernet cables (CAT5E or above) and different Ethernet ports on the main Deco.
• In the Deco app, go to MORE > ECO Mode and make sure ECO Mode is disabled.
• Go to MORE > QoS and ensure QoS is disabled. If you do not see an on/off switch, set QoS to standard and remove all priority devices.
• Go to MORE > Advanced > NAT forwarding and disable SIP ALG and UPnP.
• Try several different speedtest servers, as some may provide better results than others.

For more details, please refer to this FAQ: https://www.tp-link.com/support/faq/2429/

If you continue to experience slow speeds or if the results are not as expected, please contact TP-Link support with the results of the above troubleshooting steps so we can assist you further.