Client Spoofing
Client spoofing lets XDown present itself as another P2P client when needed.
The spoofing settings are made of three custom fields under Settings - Spoofing.

[tracker agent]: Azureus 5.7.5.0;Windows 10;Java 1.8.0_211
[id prefix]: -UT3530-
[peer client name]: uTorrent 3.5.3
tracker agent and id prefix are used in tracker requests and HTTP headers. The peer client name is what other peers see.
Only change these values when you understand the target client's identifiers; incorrect values can prevent normal downloads.