Hi OM, thanks for the debug log. (driver's author here)
The operation fails as the last byte of the ident string are not the same, look it for yourself:
DEBUG: Full ident string is:
DEBUG: 000: 50 33 37 32 30 06 fb *f1* P3720...
DEBUG: Starting the download from radio
DEBUG: Wrong Kenwood radio, ID or unknown variant
DEBUG: 000: 50 33 37 32 30 06 fb *00* P3720...
That means that the radio has the TRUNKING addon board installed. Reviewing the drivers identification schema:
"P3720\x06": (32, 450, 470, "K")
"P3720\x07": (32, 470, 490, "K1")
"P3720\x08": (32, 490, 512, "K2")
"P3720\x09": (32, 403, 430, "K3")
You can see it's like a "K" variant and must work from 450 to 470 Mhz, it's supported.
Also, the driver does not support radios with the TRUNKING addon installed (last f1 byte means that) as it changes the memory handling a bit.
If you can access the OEM software please read it, deactivate the TRUNKING option and upload the programing again.
I must work with chirp then.
Cheers, Pavel CO7WT.