@flohack I went back and checked adb connection but fastboot devices only shows the phone when it is in recovery. I noticed that when in recovery fastboot devices lists the ser. no. and has unauthorized beside it.

I managed to get UT installed on my Nexus 6p, pretty simple with the installer. I ran it for a day or so and now I'm not able to transfer files from my Debian machine to or from the phone. I tried multiple cables also tried my Rpi4 and an Ubuntu distro it worked at first then quit any ideas?