Overriding the JSON that v2rayN generates with your own config

Export a working one first

Pick a node that already works, right-click and choose to export the full configuration, then save the JSON. Editing that beats starting from a blank file: the inbound ports, log block and routing skeleton are already correct.

Import it as a custom config server

In the main window use Servers → Add custom config server, point it at that JSON file and give it a name. When it's selected, v2rayN hands the file to the core untouched — it stops assembling anything, so the routing and DNS settings in the GUI no longer apply.

Two things that bite people

• The inbounds ports in your file must match v2rayN's local ports, or the system proxy points at nothing.
• Field names change across major core releases. When startup fails, read the field name in the first log line instead of reinstalling the client.