RBR750 router with CM1200 modem - unpredictable and intermittent network speed drops

FURRYe38 

• will look into CAT6 if needed
• distance between RBR and RBS is about 35 ft in the horizontal plane, and about 6 ft in the vertical plane, on different floors, opposite corners of the house. So let's just assume a bit over 35 if my trigonometry is right.
• what will setting channels do?
• i just generally do the fw updates when the orbi app presents them to me
• Can do a full system reset if there are no other leads to pursue first
• regarding drivers - i'm also seeing the same symptom on all devices simultaneously. Phones, laptop, game console, tv, streaming sticks. It seems unlikely it's a device issue.

plemans 

• I assume you  mean power to mean the signal coming from the ISP into the modem, rather than "electrical" power to the hardware, correct?
• Both Xfinity techs noted an unusually high signal coming from the pole to the house, but both techs did some cabling rearrangement that they suggested would resolve the issue. The second tech did say he'd create a ticket to have someone look at something at the pole, but that is outside the scope of me hearing back from Xfinity about.
• Is there a specific log error or warning I can cite to Xfinity for support? Or is this something to address with my hardware?