If you are using a private tracker that imposes client restrictions, it is very easy to bypass.

Go to Settings > Transfers > Trackers > Individual Trackers Options
Then click EDIT -> then select ADVANCED OPTIONS

Now, for each private tracker you want to bypass, enter the following lines, substituting both the random-torrent-site.org and abcdefghijkl:


random-torrent-site.org
header:%0D%0AUser-Agent: Transmission/1.30X
peerid:-TR1330-abcdefghijkl
xfer_peerid:-TR1330-abcdefghijkl


It is very important to replace the abcdefghijkl part with 12 random letters/numbers.

If you need more help, please make a post in the forum.