Couldn't open NC web if download over 3 files at the same time

My NCP is setup by raspberry pi 4 , 4G RAM.
ver: 16.0.6
I found if I was downloading over 3 files at the same time, I couldn’t open NC webUI.
Does anyone have this issue?
If the PHP threads limits caused this problem?

Sounds like a power source problem. Check your power source and cable.
Are you using external usb drives? Are they self powered?
If not try connecting them thru a powered usb hub.

Hi Oliver
Thanks for your advise , I just found the problem caused by my chrome browser. I don’t know why my chrome has this bug.
IE works fine .