@lakotaubp
Thanks for the reply. Yes, I am familiar with TWRP, I have applied the wipe and reformat functions. My inquiry was about any potential specific order to apply each step, and even if you have to repeat a few, reboot TWRP in between, because I have tried plenty of times, interchanging the order, repeating steps, all to no avail.

Tried the .deb installer as well as the appimage.

@mikeglover Hi, I am currently facing the same issue. I formatted, wiped, formatted again, wiped in whatever order you can imagine, but the result is the same. "Connection lost to device".
The cable is OK, the USB port is OK, I have used them both to install a number of custom ROMs on a number of devices.

Could you specify the exact order in which you proceeded with the UT install? (i.e., first format to ext4, then wipe everything eight times, then format as ext4 twice)
Thanks in advance.

I have seen a number of posts about this issue. Someone said that the install failed because the only ext4 partition was "cache", and it fills up quickly. However, I reformatted data, system and cache to ext4, countless times, so this suggestion did not work.

Somewhere else I read something about the data partition being named "userdata", and that you have to format it directly with fastboot [ fastboot format:ext4 userdata ]. Tried this with "data" and "userdata", to no avail.

The install goes as far as leaving the UT recovery on the phone, but it does not progress from there.