[Unit]
Description=Ping to keep connection alive
Wants=network-online.target
After=network-online.target

[Service]
Type=oneshot
ExecStartPre=/usr/bin/sleep 5s
ExecStart=/usr/bin/ping -6 -c 10 ipv6.google.com
RemainAfterExit=yes

[Install]
WantedBy=multi-user.target