If you run General on Windows and configure it to use pxplus.exe, the GUI server fails to launch the pxplus command line correctly, and the main listener doesn't start. GUI clients then get an error 1057 trying to connect to the server.
1. Update the General server to a release built after June 5, 2018, or
2. In the folder where pxplus.exe is, copy pxplus.exe to pvx.exe. This copy is still the pxplus executable and runs correctly under the same activation, but is has a name that is valid for older versions of General on Windows. Then configure General to run this executable rather than pxplus.exe.
Note that this correction is just to get the server up and running. There may still be network issues causing an error 1057, such as a firewall rule blocking access to the port (default 8414).