without getting into details ..
Most all of the major ISPs are using standardized password prefixes for their customers, and in the majority of cases these do not get changed.
This makes it very easy, for bruteforce lists to be created, that common available tools can make use of to compromise networks.
These tools are widely available, and free on the internet for children.
If ISP's are not forced to stop standardizing password prefixes, I do not see how any sort of secure online activity, can ever hope to be achieved.
p.s your entire infrastructure is unsecured, and all of the copper is producing an excat copy of all information, that can be rerouted with standard twisted copper cable splitter, and the demodulator does not care which part of the split the information comes from.
So personally I have no idea how to do this, but I can confirm that every bit is available anywhere within 150ft of that modulated signal, Im sure someone can build a demodulator that will mimic the original mdm.