I have 2 units of Deco M5 (one master and one satellite). When I connect a LAN cable from my computer (Macbook Pro 2019 base model) to the main unit's Ethernet port, I get about 400-500 Mbps upload speed which is half of what I get if I connect the computer directly to ONT. I have tried to reboot everything, used different Ethernet cables, but the results are consistent.

ONT > Computer (900-950 both Down and Up; so I'm getting good bandwidth from my ISP for my 1Gbps connection.)

ONT > Deco M5 > Computer (750-900 Down and 330-450 Up); Sometimes it touches 500 upload, and the max upload I've seen is 650 in one rare case.

I have read another similar post and followed all the instructions in that post to make the following observations:

1. The Deco units are in Router mode.

2. When running the speed test within the Deco app, I get about 780-800 Down and 930-950 Up (though direct ONT connection to my computer gives 900-950 Down and Up).

3. My Deco units are running the latest firmware version noted above.

4. I have tested with the satellite unit turned off and it didn't make much difference.

5. The QoS is set to Standard and limits are set to 1024 Down and 1024 Up.

6. I'm using speedtest dot net for my testing.

7. With Google speed test, the download speeds are similar (750-800) but uploads are even worse (150-200).

8. I've tried to set my computer as a High Priority device under QoS but it didn't make any noticeable difference.

9. Replaced the main deco with the satellite deco (following the instructions in the FAQ) and tested by connecting the computer to the new main (previous satellite) deco and the results are about the same.

I think I've tried everything short of resetting the routers completely. I really don't want to lose all my configs.

If the upload was even 25% slower than the ISP bandwidth, I would accept it, but this is 50-60% slower.

Please let me know what can be done to resolve this. Thanks.