TCP packet loss when ESP32 works in STA mode

[poltroon]

My application samples ADC every 1 ms and sends out the sampled data over TCP every 100ms. The length of the TCP packet is about 200 bytes. At first, I configured ESP32 to work in STA mode and connected both ESP32 and my computer to the wireless router. On my computer I used wireshark to monitor the TCP packets between ESP32 and my computer and observed TCP packet loss/retransmission frequently. Then I configured ESP32 to work in AP mode and connected my computer to ESP32. This time, there was almost no packet loss/retransmission. I also tried using one ESP32 (ESP32 A) as wireless router and connect another ESP32 (ESP32 B) and my computer to it. In this case, there was no packet loss between ESP32 B and my computer.

It seems the problem is with the wireless router I am using. I have tried several wireless router, including TP-LINK enterprise level router, and the result was the same - TCP packet loss/retransmission observed frequently. Just wonder has anyone observed similar issue? What the root cause could be?