Linear power supplies....Bio safe voltage.

Marc Martin wrote

Yes, for me, DSL was the worst, and it got progressively worse as the speeds increased.  For that, the telephone wiring throughout the house was causing me issues.

I had the same problem, although the one saving grace of this place is that it was possible to separate the DSL and phone signals right where they entered the house. I used a bunch of filters to reduce the amount of DSL noise getting into the phone wiring, but it still wasn't great.

Plop Plop, I just noticed that two of my Antek 12V transformers have electrostatic shields (which might help with RF issues):

https://canadatransformers.com/what-is-electrostatic-shield

Another type to look into for RF attenuation would be "split bobbin" transformers. They would have a higher magnetic field than a toroidal isolation transformer, but they're very cheap.