My current ISP (Movistar) has a really bad system that crashes the connection every 5 or 10 minutes, my solution is this python script that pings google and restarts the connection when the ping fails.

stupid_movistar.py

#!/usr/bin/python
import os
import time

def checkConnection ():
    return os.system("ping -c 1 google.com") == 0

def connect():
    os.system("nmcli con up 'Movistar Default'")

while(True):
    time.sleep(3)
    if not checkConnection() :
        print "connection trouble detected, restarting..."
        connect()
        time.sleep(15)
    else:
        print "connected"