MAVProxy hold on to TCP port after port is removed or disconnected (Windows)

We use MAVProxy to multiplex telemetry data from a 433MHz link (COM) and a 5,8GHz link (TCP).
If the TCP link goes down there is no way of reconnecting other than to restart MAVProxy. When MAVProxy is restarted we have to reconnect MissionPlanner and reload all parameters. This takes time and leaves us with no link while restarting. Flight data is also reset.

There should be a way to reconnect TCP links without restarting MAVProxy. MAVProxys process holds on to the TCP port even if the link is down, and is unable to reconnect. Running on Windows 10.

Start by tracing MAVProxy's TCP link connection and disconnection handling on Windows, focusing on how the process releases and reopens the port after a link goes down. Done means a disconnected TCP link can reconnect without restarting MAVProxy, while the existing MissionPlanner connection, parameters, and flight data remain available.

Written by the indexing model from the issue text.