I just got a TrueRNG v3, and I’ve been trying to set it up with a Linux laptop running Ubuntu 20.04. I’ve followed the installation instructions, including adding HRNGDEVICE=/dev/TrueRNG to /etc/default/rng-tools. Still, rng-tools tries to read data from /dev/hwrng instead, so rngd issues a bunch of read errors in /var/log/syslog.
It doesn’t appear to be a problem with the TrueRNG unit; if I start rngd from the command line and specify /dev/TrueRNG as an argument it runs. But there’s either a problem with the rng-tools package or with the documentation.