Date

Many BitTorrent trackers don't really support IPv6. Since they run behind Cloudflare or similar for load balancing, this causes issues.

Systemd added a feature called RestrictAddressFamilies that will filter out some address families, for example IPv6, from a unit.

[Unit]
Description=Transmission BitTorrent Daemon
After=network.target

[Service]
Type=notify
ExecStart=/usr/bin/transmission-daemon -f --log-info
ExecReload=/bin/kill -s HUP $MAINPID
TimerSlackNSec=1s
PrivateTmp=true
#PrivateDevices=true
ProtectSystem=full
IOSchedulingClass=idle
CPUSchedulingPolicy=batch
RestrictAddressFamilies=~AF_INET6
LimitNOFILE=8096

[Install]
WantedBy=default.target

The above block will do a lot of different things, but the important part here is RetrictAddressFamilies.