I have bought hAP lite then connected it to my existing network with default configuration, my network diagram is attached.

Router OS: 6.27
Quick Set: Home AP
Ether1 connect to network with ip 10.1.0.2/24
Router internal IP: 192.168.88.1/24
Ether2-4 and Wifi are bridged with dhcp assign ip: 192.168.88.2 - 192.168.88.242/24
Firewall: Default
NAT: Default (masquerade)

I have started testing download file on PC1 from external server on the internet via HTTP and FTP and download speed is about 18 Mbps but when I try to upload via HTTP and FTP, speed is just 5 KBps and finally timeout without successfully so I think it could be a problem with my RB941-2nD then I have tested download/upload file from internal FTP server IP 10.1.0.3/24 and download/upload speed is 90-100 Mbps so it seems not about my RB941-2nD?

I have tested again by remove RB941-2nD and connect PC1 directly to switch and gateway assigned my PC1 with ip 10.1.0.4/24 then I try to download from external server on the internet via HTTP and FTP again but this time download/upload speed is 20/6 Mbps and files are uploaded/downloaded successfully without any problem.

Do you guy have any idea what cause problem? I have tried to reset my RB941-2nD many time but it wasn't solve external server upload problem.