Error 10054 means that the connection between VPOP3 and a remote computer (eg the ISP or another computer on your LAN) was disconnected by something outside of VPOP3.

This is almost always caused by anti-virus software on the vPOP3 machine but it could be any of a number of things. Any software that is sitting between vPOP3 and the ISP could be the root cause.

It could also mean that the remote computer itself decided to drop the connection abruptly, or that the network connection failed unexpectedly (or that the user dropped the network connection manually).