Since a "one-click link" doesn't exist, here are the actual methods used by technicians to unlock these devices.
Before starting, check your current firmware version by logging into the router and looking at Device Information.
For the ZTE ZXV10 B866V2, the most famous "free unlock" is enabling Telnet (a command line interface). This gives you Linux-level access.
The Free "Link" (Script): You don't need a website; you need a tool. You must use a specific HTTP request to enable Telnet.
Note: This specific CGI script works on many ZTE GPON models, but the B866V2 may be patched. If that fails, you need older firmware.
Once Telnet is open (Port 23):
Once inside Telnet, you can run commands to:
Device Type
Optical Network Terminal (ONT) / Home Gateway Unit, often provided by ISPs (e.g., China Telecom, China Unicom) for fiber broadband.
Common Locking Reasons
There are three technical reasons a simple link doesn't work for the B866V2: