CM1200 Internet Issues: Intermittent Slow, or Disconnection - Spectrum

FURRYe38 ,So, my wiring is all hidden, I'm not sure what it's doing behind enclosed drywall.   So while I'd like to believe that it's a straight shot, I'm not sure.   So before I start tearing my walls apart (joking) fishing wires through the wall, I'd like to know if singnals look good coming into the modem. 

To be clear, I've tested from the Ookla app, using my ISP cloest location from my laptop running hardwired directly into the cable modem, with wireless disabled.   

As to this

"Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly."

The two technicians both respond to me that it's not great, but it's within range.   Which I have don't know what the means.  I just feel like they don't actually want to check or repair anything, and I don't know enough to prove otherwise. 

Specific to

"Ensure LAG is disabled on the CM modem"

I'm not sure what this is, maybe you can explain?