Disconnecting causes "The requested address is not valid in its context." TCP error

I have NextDNS run at startup on a W10 machine and have the following issues:

1. At first, the internet does not work. When I try to load a page, the browser says that it cannot reach the destination.

2. If I try to disconnect NextDNS (by right clicking  the system tray), it throws this error message:

dial udp 192.0.2.43:2222-> 192.0.2.42:2222: bind: The requested address is not valid in its context.

3. If I kill the process with Task Manager and re-launch NextDNS.exe, then I it throws this error:

windows.CreateFile: A device attached to the system is not functioning.

4. Only upon restarting the service do all of these problems go away and does the application work as expected. 

Any idea what might be causing this? Googling the Bind error shows it is a TCP configuration issue, that it is attempting to bind to an address that doesn't exit. Others recommend binding to something like 0.0.0.0 instead.