<<< Data frame from KISS client application, port 8, total length = 18 000: 80 84 90 64 ac 94 ae e0 84 90 64 ac 94 ae 61 3f ...d......d...a? 010: 0a d0 .. Invalid transmit channel 2 from KISS client app.
Are you using AX.25 for Linux? It might be trying to use a modified version of KISS which uses the channel field differently than the original KISS protocol specification. The solution might be to use a command like "kissparms -c 1 -p radio" to set CRC none mode. Another way of doing this is pre-loading the "kiss" kernel module with CRC disabled: sudo /sbin/modprobe -q mkiss crc_force=1
Sets the FEC error correction level in a DSP card based modem (KISS parameter 8). Larger correction level means better noise resistance, but slower throughput on a good connection. This is an experimental feature found in a QPSK modem for the Motorola DSP56001 based DSP4 and EVM cards only.