Ethernet Wiring

@lovehifi22 ,

Project status?   

The cable would be inserted into the duct about 15’ away from the furnace plenum.

I assume a straight shot through a 6" dia round supply duct to a ceiling mounted outlet vent register? (Naturally the ceiling register would be remove when installing a fish tape to pull in the data cable.)

Good luck if you first have to travel through a main supply duct to the tap off for the 6" dia round branch duct that feeds the ceiling register.

FWIW, I would recommend you purchase the data cable from Blue Jeans Cable. They will make you a cable cut to length and install RJ45 plugs on each end of the cable. Cable will then be tested to make sure it meets specs standards. Not just a wire mapping test.

Protect both connectors so they are not damaged during installation. 

I’m retired now but at my last work place they ran cat 5 through the building ducts and it was a huge improvement over the previously horrible WiFi that we had.  There were no issues over the year and a half of use before my retirement.  I chatted with installer who said that they do this all the time.  He said that he had never encountered an issue with warping due to HVAC, which was the first question that I asked.

  Ethernet cable is inexpensive.  Even if something did warp after years of use, replacing it should not be to painful 

Thanks to all for your helpful comments and suggestions. 
Greatly appreciated. 

@zlone

Is it possible that the TP-Link extender is introducing noise into your electrical power?  Similar to what dimmers do in home wiring?

Are you using any power conditioners?

@boulder_bob I have no doubts that the TP-Link is probably a bit noisy, but my house likely has several other devices that are just as bad. I spent last year working on my power and tried Furman, Puritan, but then settled on a PS Audio P15 regenerator. That pretty much fixed everything, Sunday night sound all the time now.