I teach a class using the BRX PLC. Now that everyone has to use the USB ethernet adapters, the network connection will drop and is far from consistent. Are there any fixes for this problem?

Have you tested the hardware independently from the VTScada connection to verify where you are having an issue? I use a dongle on my business PC which regularly connects to different devices over TCP/IP and I haven't noted any issue with my connections. Note that your class could also use a wireless adaptor and switch to connect the devices. One thing to note is that some PLCs only support a finite number of simultaneous connections (often the default may be one connection).

Let me know if that is helpful.

I have tested the connection with the Ethernet cables, it is just when we use the USB Ethernet adapters that I am having connection issues.

VTScada, like all Windows applications does not care what provides the Ethernet connection, that is all handled by the Windows drivers.

At this point I would concentrate on the USB hardware and associated driver in an attempt to eliminate those as suspects.