I'm having trouble getting my TNC-X clone to work properly with Direwolf on a Raspberry Pi 4. When I power cycle the TNC, I see several lines of initialization text, but after doing an alt-SETUP-TNC command to initialize the TNC parameters, packets aren't decoding correctly.

The TNC seems to receive data (DCD light flashes), but Direwolf isn't seeing valid KISS frames. I've verified the serial connection at 9600 baud and tried both hardware and software flow control settings. I've checked that no other monitoring features are inserting extra data into packets, and added custom parameters to the InitTAPR.TNC file.

Has anyone successfully configured this combination? I'm wondering if there's a specific KISS parameter I'm missing or if the TNC-X firmware needs updating for proper Direwolf compatibility.

Check your parity settings - standard TAPR TNCs need PARITY 0, but some like the KAM need PARITY 4. Also make sure HEADERLINE is set to OFF if your data isn't appearing on the same line as the header. The TNC-X can be finicky about KISS mode initialization.

I've seen this exact issue! The problem is often that the TNC-X isn't properly entering KISS mode. Try sending "KISS ON" manually through the serial terminal before starting Direwolf. Also verify your audio levels - APRS has no error correction, so excessive packets or poor audio means lost packets forever.

Consider trying APRS TNC Web - it's a lightweight, Docker-powered web application that gives you a clean, modern interface to interact with APRS traffic using any KISS-compatible TNC. It might help you troubleshoot whether the issue is with Direwolf or the TNC configuration itself.