Advanced settings:

peerid:-TR2940-
xfer_peerid:-TR2940-

Log:

"peer-id set to -TR2940-_E_{_(ɕlv__", where random part of peerid is actually URLencoded.

Ooops! This is non-standard, I presume. Detected and banned at two private trackers. Can it be non-urlencoded, at least?

Lack of header may be the reason, you should use it too. For the random part I think it's safest to fill all characters (as static).

See this topic for an example: https://forum.tixati.com/support/2908

**************.org
header:%0D%0AUser-Agent: Transmission/2.94
peerid:-TR2940-c1**********d2
xfer_peerid:-TR2940-c1**********d2

Works as expected, but lacks randomness.

**************.org
header:%0D%0AUser-Agent: Transmission/2.94
peerid:-TR2940-
xfer_peerid:-TR2940-

Gives random part after -TR2940-, but this random part is: a) not alphanumeric charset; b) URLencoded.