Firewall-php how to run the program in the background

The following code allows others to access the network on their mobile phones first, but I want to delete the records in the firewall 60 minutes after nohup, so that others must connect to the network once every 60 minutes. But now the problem is that nohup does not work, and the firewall cannot automatically delete records after a specified time. I am a newbie now. please help me! Thank you! Run iptables in the php background of the firewall

The following code allows others to access the network on their mobile phones first, but I want to delete the records in the firewall 60 minutes after nohup, so that others must connect to the network once every 60 minutes.
$ Iipp = $ _ SERVER ["REMOTE_ADDR"];
Exec ("iptables-t nat-I PREROUTING-s $ iipp-j ACCEPT ");
Exec ("nohup sleep 60 m>/dev/null 2> & 1 &");
Exec ("nohup iptables-t nat-d prerouting-s $ iipp-j ACCEPT>/dev/null 2> & 1 &");
?>

But now the problem is that nohup does not work, and the firewall cannot automatically delete records after a specified time. I am a newbie now. please help me! Thank you!