EDIT: Before going into the details, see 397429/28 comment.
Wanted to share the link to a working ZigBee coodinator (the device that is required to connect zigbee devices to HA) I’ve found on AliExpress that works in lan-only and does not need to be connected to your server via USB (it works over ethernet).
http://aliexpress.com/item/4000465421911.html (Moes Tuya ZigBee Smart Gateway Hub Smart Home Bridge Smart Life APP Wireless Remote Controller Works with Alexa Google Home, Wired Hub model)
It can be hacked by following this tutorial (steps are 100% identical. the board has visible differences, but pins location and instructions are completely identical): Tuya Ethernet Zigbee Gateway TYGWZ-01 Zigbee compatibility