Calibre Companion & Windows & Linux

[jvik]

I've got a Windows box (W11) and a Linux box (MX 23) with Calibre installed on each. I can connect to the Windows instance from my Galaxy S9 tablet with Calibre Campanion. With connection settings for wireless connection set to auto, when I start a wireless connection CC detects both instances of Calibre and lets me choose. Connections to Windows work great, but if I choose the Linux instance it fails to connect

If I specify a specific IP/Port in CC for the Linux box it still won't connect. I can ping that IP from other devices just fine. Anyone have any ideas?