:local PPPInter "ppp-out1";# jmeno PPP interface
:local count 0;
:local IP  [/ip address get [find interface=$PPPInter] address];
:local IP [:pick $IP 0 [:find $IP "/"]]

: log warning  "address current is $IP";

:if ([/ping $IP count=5] = 0) do={ : log warning  "ping test negative";
  /interface disable $PPPInter;
  :delay 5s; 
  /interface enable $PPPInter;
} else={: log warning  "test ping O.K"}

: log warning  "end of test ping";
:delay 30s

:while ( $count < 3 )  do={ 
   /interface ppp-client monitor $PPPInter once do={:if ($status != "connected") do= {:set count ($count+1); :log warning  "PPP $PPPInter Link Down (#$count)"; :delay 10; } else={ :set count 4; } };
}
:if ( $count > 0 && $count <4 ) do={ 
   :log warning "PPP Link Down, Resetting USB Port"; 
   /system routerboard usb power-reset duration=10;
}
:delay 120s;
:log warning  "end of test PPP interface."