Place the following file in /srv/unifi/data/sites/default*/ on the CloudKey:
config.gateway.json
{
"system": {
"task-scheduler": {
"task": {
"pppoe-disc": {
"crontab-spec": "0 3 * * * ",
"executable": {
"path": "/usr/bin/killall -HUP pppd"
}
}
}
}
}
}
*default or your site name.