Player version 2.2.1 onwards used new socket.io (2+ version) by default and if does not work falls back to 0.9.x version.
New version needs http:// prefix to the server name for new version to work. e.g. http://192.168.0.100:3000 or http://myserver.com:3000
Simple address is appended with https prefix, for e.g. 192.168.0.110:3000 defaults to https://192.168.0.100:3000