SWM splitter, LNB, or bad cable?

My Gemini's DECA (cable to ethernet adapter) stopped working.  Tested with both a gemini and a laptop.  Swapping it out the DECA didn't help.   The DECA was the old style that has power and usb-power connectors.

A couple of weeks prior, I had repaired a cable that the lawn mowing people cut.

I took a look at another room.   An old genie mini was working when connected via cable - but not if I tried to put either of two new-style DECAs (DCA2SR0) in-line on the cable.  Nor does the power light on that DECA come on.

Next, the problem got worse - I got a 775 problem between the Genie-2 and the dish.  Disconnecting the cable from the SWM splitter and connecting it directly to the Genie-2 solved that problem.

I'm guessing the signal levels and maybe the voltage levels on the cabling are/were poor.

But, is it the cable or the SWM?  Or, even maybe the LNB or Genie-2 ?