The issue is unable to download large file completely from download.wetransfer.com. The download stopped half way (at approximately 40-50%) with 0 B/s download speed.
For example, a zip file size 120MB with following download URL stopped at ~50MB and download speed become 0 B/s.
The Origin Content Server (OCS) URL is download.wetransfer.com
Resolved IP Address is 220.127.116.11 (NOTE: IP is subject to change)
Packet capture file shows following Expert Information in wireshark using display filter: (tcp.analysis.window_full || tcp.analysis.zero_window)
[TCP Window Full] - TCP window specified by the receiver is now completely full
[TCP ZeroWindow] - TCP Zero Window segment
Source: OCS (URL: download.wetransfer.com, IP: 18.104.22.168)
The frame with [TCP Window Full] indicates the Upstream OCS has completely filled the receive buffer of ProxySG.
[TCP ZeroWindow] means ProxySG sends an ACK to the Upstream with a window size of 0. This means that the window size will remain at 0 for a specified amount of time, ProxySG unable to receive any more data at this moment, and the TCP transmission is halted until it can process the information in its receive buffer.