Hi,

I recently bought the Archer C4000. The main reason I'm upgrading is to improve my LAN file transfer performance. I don't care about the ISP speed as that's already satisfactory to me (ISP is 100/100 Mbps, and I get about 70/90 Mbps from speedtest.com). However, I am getting drastically poor LAN file transfer speed from one computer to another, all connected to the same C4000 router. 

Here's a brief description of my setup: I have my Mac server hooked up to the C4000 via ethernet cable, and other laptop and devices connected to the router via Wifi. There are about 10 total devices connected to the router, but only about 4 of them share the two 5Ghz AP including the laptop. 

ISP gateway --- ethernet cable --- C4000 router --- ethernet cable --- mac server

                                                                |  wifi 

                                                      laptop, phones, etc

After setup, I tested LAN speed between the laptop and the Mac server using iperf3. When tested on the laptop, the read (download) speed from the local Mac server is reasonable (~600 Mbps, ~70 MB/s), however, the write (upload) speed is very slow (maxed out at 200 Mbps when laptop is close to router. Using my previous router, I was able to achieve ~300 Mbps upload with the same setup, so I don't think the bottleneck is with the Mac server, or its hard drive (SSD). 

So it seems the LAN tranfer speed for the C4000 is throttled at one direction (laptop --wifi--> router --cable--> server) but not the other way around. Is there any settings on C4000 I can tweak to lift this throttling? What I already tried:

1. disabling firewall and antivirus on the HomeCare

2. disabling all ALG NAT forwarding

3. setting QoS to default (application priority to standard, device priority to none, and bandwidth to 1000 Mbps both)

4. enabling and disabling airtime fairness and MU MIMO for the two 5Ghz wifi AP.

But none above helps. I also contacted TP-Link chat customer service regarding the issue but the rep kept telling me to bypass the router and test ISP upload speed, which I believe won't help with my LAN problem. 

I really hate to return this unit to Costco as all other aspects of performance are very satisfactory. But improving the LAN backup speed from my laptop to the server is one main reason I bought it and it's failing miserably. 

Thanks,

Steven