I’ve been using ser2net with a serial to usb cable for over a year with my Resound CAV. The integration only supports a single unit at the moment, the underlying library supports multiple units but the HA integration hard codes the unit id to 1. I’ve been meaning to get around to updating it but haven’t had a chance.
I’m currently running my HA on a rpi4 and use the portainer add-on to run a ser2net container to expose my Resound unit.
My /etc/ser2net.conf:
BANNER:banner:\r\nser2net port \p device \d [\s] (Debian GNU/Linux)\r\n\r\n
3333:telnet:0:/dev/ttyUSB0:19200 8DATABITS NONE 1STOPBIT banner
I work with docker on a daily basis so it was easiest for me, have to mount the rpi4 USB device in portainer to /dev/ttyUSB0.