255.255.255.0, or 1111111 1111111 11111111 00000000 in binary, means that in terms of addresses 192.168.3.10 is on a different "network" (for routing purposes) than 192.168.2.10. Addresses for that first network run from 192.168.3.0 through 192.168.3.255. The first and last addresses are reserved with special meanings. Don't use them. 192.168.3.1 through 192.168.3.254 are usable.  In terms of Pluto I am not sure how it works as I've not run it lately. It does act as if it has a network built into it. (Of course, it can work as a wireless modem.) If  you have crammed a USB to Ethernet adapter on it ask other people how to set that up. I refuse to do it as I would get 1/5th the throughput for data severely limiting sample rates. However, that Ethernet link would have to be setup to work on the same network, hypothetically from the above discussion 192.168.3.xx. Otherwise it will be tuned out by your PC's networking hardware.

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