Hi to all. Many thanks for your reply. I will try to explain better the scenario. Yesterday I was to tired.
So, the diagram are the following:
Supplier Router <-> Archer C7 <-> WDR3600/841N
The connection between Suplier Router and Archer C7 is a LAN <-> WAN and WDR3600 and 841N are connect to LAN port of Archer C7 as an AP.
But, my issue are why the download speed is lower that upload speed when I connect to WDR3600 or 841N? On Archer C7 I have software flow-offloading enabled.
I make many test with that, so lets put it.
Old Desktop Pentium by Cable to Archer C7 - 450Mb
New Laptop DELL i7 by Cable to Archer C7 - 450Mb
Laptop by WIFI to Archer C7 - 215 download and 100 upload
Laptop by Cable to TL-841N - 47 download and 94 upload
Laptop by WIFI to TL-841 - 26 download and 75 upload
Mobile XIAOMI M10 to Archer C7 - 204 download and 105 upload
M10 to TL-841N - 28 download and 70 upload
A old Toshiba Laptop to WDR-3600 by WIFI - Between 50-80 download and 95 upload.
So, with Speedtest the Archer can handle the 450Mb by cable and 200Mb by WIFI on a 5Ghz network but when I move to put and router as an access point front of it, by cable or wifi the download speed is worst that upload speed.
Also, i make tests with IPREF3, lest put some of them.
Between Laptop and Desktop the speed goes from 600-830Mb depending the flow direction, connected by cable and trough Archer C7.
By direction I use the reverse function on IPREF3.
If I put the TL-841 on the middle by cable or by WIFI the speed on both ways is around 80Mb
If I try with my mobile M10 with Desktop I have around 250Mb on both ways.
As I can see, with small differences of 10Mb, the speed between upload and download are smaller.
Now, I put my Laptop on the same zone of the supplier router, meaning that it was connected to a port tagged to the same network where are the WAN port. So, any traffic need to passe by firewall.
Here, I have the same behavior.
If I connect directly to Archer C7 I have:
Desktop to Laptop 424Mb download and 440 upload
Mobile M10 Laptop 135 download and 163 upload
But, when I put the TL-841 on the way I have
Desktop to Laptop 22Mb download and 94 upload
Mobile M10 Laptop 30 download and 72 upload
Once more the download is less that upload.
With SpeedTest I made some test with and with out the software flow-offloading activated but the behavior are the same.
On Openwrt 18 I think I did not have this but on that time I have only a 200Mb/100Mb speed and I did not care to take much of them and did not make tests. Now, I am restructuring all my network to get the most of 500 and I get this,
Could be something regarding QoS or something? The AP have the DHCP and DNS services down.
Many thaks for your help and I hope that I can explain better now the issue.